Latitude and longitude

Synopsis : Bees don’t use a diary. Colony development is influenced by local environmental conditions. These are largely determined by latitude and longitude but also vary from year to year. Understanding these influences, and learning how to read the year to year differences, should help you judge colony development. You’ll be better prepared for swarm prevention and control, and might be able to to identify minor problems before they become major problems.


Writing a weekly post on beekeeping inevitably generates comments and questions. Over the last 5 years I’ve received about 2500 responses to posts and at least double that in email correspondence. That works out at ~30 comments or questions a week 1.

Every one of them – other than the hate mail and adverts 2 – has received a reply, either online or by email.

Some are easy to deal with.

It takes just seconds to thank someone for a ”Great post, now I understand” comment, or to answer the ”Where do I send the cheque? question.

Others are more difficult … and the most difficult of all are those which ask me to diagnose something about their hive.

I almost always prefix my response by pointing out that this sort of online diagnosis is – at best – an inexact art 3.

Patchy brood pattern

Patchy brood & QC’s …

Think about it … is your definition of any of the following the same as mine?

  • a strong colony 4
  • an aggressive colony
  • a dodgy-looking brood pattern 5
  • a ‘large’ queen cell

Probably not.

Engaging in to and fro correspondence to define all these things isn’t really practical in a week containing a measly seven 24 hour days.


However, having stated those caveats, there’s still the tricky issue of geography.

Many correspondents don’t mention where the hive is – north, south, east, west (or in a couple of instances that they are in the southern hemisphere 6).

Location has a fundamental impact on your bees. The temperature, rainfall, forage availability etc. all interact and influence colony development. They therefore determine the timing of what happens when in the colony.

And so this week I decided to write a little bit about the timings of, and variation in, environmental events that influence what’s going on inside the hive.

I’ll focus here on latitude and temperature as it probably has the greatest influence. My comments and examples will all be UK based as it’s where a fraction over 50% of the readers are, but the points are relevant in all temperate areas.


Temperate climates – essentially 40°-60° north or south of the equator – experience greater temperature ranges through the year and have distinct seasons (at least when compared with tropical areas). Whilst latitude alone plays a significant role in the temperature range – smaller nearer the equator – the prevailing wind, altitude, sea currents and continentality 7 also have an important influence.

For starters let’s consider the duration of the year during which foraging might be possible. I’ll ignore whether there’s any forage actually available, but just look at the temperature over the season at the northern and southern ends of mainland Great Britain.

I arbitrarily chose Thurso (58.596°N 3.521°W) and Penzance (50.119°N 5.537°W) for these comparisons. Both are lovely coastal towns and both are home to native black bees, Apis mellifera mellifera 8.

The lowest temperature I have observed my native black bees flying on the west coast of Scotland was about 8°C 9. So, let’s assume that the ‘potential foraging’ season is defined by an average maximum daily temperature above 8°C.

How do Penzance and Thurso compare?

Thurso – average Max/Min temperatures (°C)

In Thurso there are eight months (November just squeezed in by 0.1°C) where the average maximum daily temperature exceeds 8°C.

Penzance – average Max/Min temperatures (°C)

In contrast, every month of the year in Penzance has an average maximum daily temperature exceeding 8°C.

Thurso and Penzance are just 950 km apart as the bee flies.

Forage availability

I don’t have information on the forage available to bees in Penzance or Thurso, but I’m sure that gorse is present in both locations. The great thing about gorse is that it flowers all year, or – more accurately – individual, genetically distinct, plants can be found every month of the year in flower.

Based upon the temperature it’s possible that Penzance bees could forage on gorse in midwinter and so be bringing fresh pollen into the hive for brood rearing.

The gorse is in flower … somewhere under there

However, further north, gorse might be flowering but conditions may well not be conducive for foraging.

Inevitably, warmer temperatures will extend the range of forage types available, so increasing the time during the year in which brood rearing can occur 10.

In reality, at temperatures below 12-14°C bees start to cluster 11 and bees chilled to 10°C cannot fly. It’s unlikely much foraging could be achieved at the 8°C used in the examples above 12.

The point is that different latitudes differ greatly in their temperature, and hence the forage that grows, the time it yields nectar and pollen, and the ability of the bees to access it.

Brood rearing

The availability of forage has a fundamental impact on the ability of the colony to rear large amounts of new brood.

It’s not until foraging starts in earnest that brood rearing can really ramp up.

Similarly, low temperatures in autumn, reduce the availability of nectars and ability of bees to forage, so curtailing brood rearing 13.

And the ability to effectively treat mites in the winter is largely determined by the presence or absence of sealed brood. If there is sealed brood in the colony there will also be mites gorging themselves on the capped pupae. These mites are untouched by the ‘usual’ winter miticide, oxalic acid.

Therefore, effective midwinter mite management should be much easier in Thurso than Penzance.

I’ve not kept bees in either of those locations, but I know my bees in Fife (56°N) are reliably broodless at some point between late October and mid-December. Varroa management is therefore relatively straightforward, and Varroa levels are under control throughout the season.

In contrast, when I kept bees in Warwickshire (52°N) there were some winters when brood was always present, and Varroa control was consequently more difficult. Ineffective control in the winter results in higher levels of mites earlier in the season.

Brood rearing models

To emphasise the differences here are two images generated from Randy Oliver’s online Varroa Model, just showing the amounts of brood in all stages and adult bees 14. The overall colony sizes and amount of brood reared are about the same, but the ‘hard winter’ colony (no foraging for five months) is broodless for a much greater period.

The brood and bee population in hives that experience ‘default’ and ‘hard’ winters

Without knowing something about the latitude and/or the likelihood of there being capped brood present in the hive, it’s impossible to give really meaningful answers to questions about winter mite treatment.

This also has a bearing on when you conduct your first inspections of the season.

It is also relevant when comparing what other beekeepers are discussing on social media – e.g. those ’8 frames of brood’ I mentioned last week. If it’s early April and they’re in Penzance (or Perigord) then it might be understandable, but if you’re in Thurso don’t feel pressurised into checking your own colonies as it may well be too early to determine anything meaningful.

Year on year variation

But it’s now approaching late April and most beekeepers will be starting to think/worry about swarm control.

When should you start swarm prevention and, once that fails, when must you apply swarm control?

Or, if you’d prefer to take a more upbeat view of things, when might you expect your bait hives to be successful and when should you start queen rearing?

Again, like almost everything to do with beekeeping, dates are pretty meaningless as your colonies are not basing their expansion and swarm preparations on the calendar.

They are responding to the environmental conditions in your particular locality and in that particular year.

Which brings me to year on year variation.

Not every year is the same.

Some seasons are warmer than others – the spring might be ‘early’ or there might be an ‘Indian summer’. In these instances foraging and brood rearing are likely to start earlier or finish later.

One way to view these differences is to look at the Met Office climate anomaly maps. These show how different the climate – temperature, rainfall, sunshine etc. – can be from year to year when compared to a 30 year average.

Met Office anomaly charts – spring temperatures 2020 and 2021 (compared to 30 year averages)

Here are the anomaly maps for the last two springs. For almost all of the country 2020 was unusually warm. Penzance was 1.5°C warmer than the 30 year average. In contrast, over much of the country, 2021 was cooler than the 1990-2010 average.

So when considering how the colony is developing it’s important to consider the local conditions.

Those Met Office charts are retrospective … for example, you cannot see how this spring compares with previous years (at least, not yet 15.).


And, while we’re on the subject of anomalies … here are the rainfall charts for the summers of 2012 and 2021.

Met Office anomaly charts – summer rainfall 2012 and 2021 (compared to 30 year averages)

I suspect that both were rather poor years for honey. 2012 was – with the exception of Thurso! – exceedingly wet. My records for that year don’t include honey yield 16.

Last year was generally dry, and very dry in the north and west 17. Since a good nectar flow often needs moisture in the soil it may have been poor for many beekeepers.

It was my first full season on the west coast and the heather honey yield was disappointing (but it’s not a great heather area and I’ve nothing to compare it with … perhaps I’ll be disappointed every year?). However, I managed a record summer honey crop in Fife from a reduced number of hives. Quite a bit of this was from lime which I always think of as needing rain to get a good flow from, so perhaps the little rain we did have was at the right time.

Local weather and longitude

If you really want to know what the weather has been doing in your area you probably need something more fine-grained and detailed than a Met Office chart. There are very large numbers of ‘personal weather stations’, many of which share the data they generate with websites such as or

Find one by searching these sites and you’ll be able to access recent and historical weather data to help you determine whether colony build up is slow because it’s been colder and wetter than usual. Or – if the conditions have been ideal (or at least normal) but the colony is struggling – whether the queen is failing, if there’s too much competition for forage in the neighbourhood, or if there might be disease issues.

Of course, judgements like these mean you need to have good records year on year, so you know what to expect.

My main apiary on the west coast has it’s own weather station.

Weather station and a typical west coast sky

To emphasise the local influence of prevailing winds and warm sea currents it’s interesting to note that my west and east coast apiaries – which are at almost the same latitude 18 – experience significantly different amounts of rainfall.

We had >270 mm of rain in November 2021 on the west coast, compared to ~55 mm on the east. In July 2021 the figures were 43 mm and 7 mm respectively.

All of which I think makes a good argument for rearing local bees that are better adapted to the local conditions 19. That’s something I’ve discussed previously and will expand upon further another time.


Rainfall charts and meteorological tables are all a bit dull.

An additional way a beekeeper can observe the progression of the season, and judge whether the colony is likely to be developing as expected, or a bit ahead or a bit behind, is to keep a record of other environmental events.

This is phenology, meaning ‘the timing of periodic biological phenomena in relation to climatic conditions’.

  • Are frogs spawning earlier than normal?
  • When did the first snowdrops/crocus/willow flower?
  • Are the arrival dates of migrant birds earlier or later than normal?

I’m poor at identifying plants 20 so tend to focus on the animals. The locals – frogs, slow worms, toads, bats, butterflies, dragonflies – are all influenced by local conditions. Many don’t make an appearance until well into the beekeeping season.


Or perhaps I just don’t notice them?

In contrast, the avian spring migrants appear in March and April. These provide a good indication of whether the spring is ‘early’ or ‘late’.

For example, cuckoo arrived here in 2020 (a warm spring) on the 18th of April. In 2021, a cold spring, they didn’t make an appearance until the 24th.

This year, despite January to March being warmer than average, they have yet to arrive. The majority of GPS-tagged birds are still en route, having been held up by a cold start to April 21, though some have just 22 arrived in southern Scotland.

Wheatear are also several days later this year than the last couple of seasons, again suggesting that the recent cold snap has held things back.

You can read more about arrival dates of spring migrants on the BTO website.

Beekeeping is not just bees

Much of the above might not appear to be much to do with beekeeping.

But, at least indirectly, it is.

Your bees live and work in a small patch of the environment no more than 6 miles in diameter. That’s a very small area (less than 30 square miles). The local climate they experience will determine when they can forage, and what they can forage on. In turn, this influences the timing of the onset of brood rearing in the spring (or late winter), the speed with which the colony builds up, the time at which winter bees start to be reared and the duration of the winter when it’s either too cold to forage or there’s nothing to forage on (or both).

As a beekeeper you need to understand these events when you inspect (and judge the development of) your colonies. Over time, with either a good memory or reasonable hive records, you can make meaningful comparisons with previous seasons.

If your colony had ’8 frames of brood’ in mid-April 2020 (a warm year) and your records showed they swarmed on the 27th, then you are forewarned if things look similar this season.

Conversely, if spring 2020 and this year are broadly similar (and supported by your comprehensive phenological records 23 ) but your bees have just two frames of brood then something is amiss.

Of course, the very best way to determine the state of the colony is to inspect it carefully. Understanding the environmental conditions helps you know what to expect when you inspect.



  1. And, for popular posts and/or technical ’how to’ topics (and – Ahem! – the ones where I’ve got something wrong), often more.
  2. Formally, there’s been no actual hate mail, though there have been a couple of highly critical comments and one or two shall we say blunt views expressed.


    Or ‘incorrect’ opinions as I like to call them.

  3. It’s sure as hell not science.
  4. Five frames of brood or 15?
  5. Yes, spotty we can agree on, but are the empty cells backfilled with nectar, or missed by the queen? Were the cells laid up and then uncapped and the pupae cannibalised?
  6. The first question about queen cells in late November was perplexing.
  7. i.e. the size of the landmass surrounding a location.
  8. Actually, the Cornish Black bees project (not an endorsement) appears to be based in Falmouth, but is at almost an identical latitude to Penzance.
  9. These bees are pretty hardcore … they also fly in the rain, though not in the rain at 8°C.
  10. I’m not suggesting here that brood rearing cannot occur if there’s no pollen available from the environment, but the pollen stores in the hive are limited and a lot of midwinter brood rearing would soon deplete them if they are not being refilled.
  11. At least, that’s the figure often quoted, though I regularly see broken clusters through the perspex crownboards in low double digit temperatures. See also some of the hive photos in the post last week which were taken when the temperature was about 9°C
  12. If I’d used 10°C as the cutoff, the flying season in Thurso and Penzance would have been 6 and 8 months respectively.
  13. Reduced foraging, and reduced brood rearing, is a trigger for winter bee production.
  14. I’m going to discuss this software sometime later in the season.
  15. Spoiler alert … January, February and March were all warmer than average for most of the country.
  16. Perhaps they got washed away?
  17. Though it’s worth noting that Thurso’s 30% summer average rainfall is still probably quite a lot of rain!
  18. But are ~3° of longitude apart.
  19. Like snorkels …
  20. Though I can just about cope with crocus, snowdrop and willow!
  21. They are in mostly mid-France … perhaps it’s Brexit paperwork?
  22. Yesterday.
  23. I often just scrawl these in my hive records.

20 thoughts on “Latitude and longitude

  1. Kevin

    Great article with tonnes of good info – thx. Here in Southern Ontario, Canada, we are having a later spring than normal – whatever that is, and I suspect that our swarm season will be about 10 days later than usual, which is around June 8-12th based on my records of catching swarms. I will be putting out traps same time, beginning of May and will see how this plays out. Local is so important for beekeeping and also all of agriculture in general.
    Keep up the good work,

    1. David Post author

      Hi Kevin

      Always good to have the swarm traps (bait hives) out well in advance of the swarming starting. I’m sure the scout bees start their work before the colony swarms. It always feels good to have an idea when everything is going to get a bit manic, so you can be prepared and enjoy the anticipation 🙂


  2. Jorge

    Another great post!
    Here, southern Portugal, the swarm period is almost in its end.

    My best hives are with five supers already.

    After a very dry winter, april bring the very needed Rain.

    Ir will extend the forraging period.

    1. David Post author

      Hi Jorge

      Five supers … the five colonies I have in one of my apiaries here might not need five supers between them! Swarming on the east coast here will probably be early/mid May, but later still on the west coast (he writes confidently … Ha!).

      I’ve seen a lot of beekeepers in the mountainous regions of Spain using one box Layens hives. Presumably you use Langstroth’s or something similar.


      1. Jorge

        My bees are in “Reversível” and Langstroth hives.

        The 5 supers are in my best reversível hive.

        The best langstroth hive have currently 3 supers above the nest.

        For your reference, the Reversível box is as wide as Langstroth but it’s shorter , it is a square box with the same height as the LAngstroth box.

        1. David Post author

          Thanks Jorge

          Reversível was a new hive type to me. I looked it up on a manufacturers website and was amazed at the price. In the UK a hive like that would cost 3 – 4 times the price for an economy model, and ten times the price for a top quality cedar box.


  3. Archie McLellan

    Hi David

    Thanks for the clarification about gorse. I’ve always wondered what miraculous property this plant had.

    I’ve been noticing (but not recording) the temperatures at which bees have been flying in the first months of this year. It strikes me that simply referring to air temperature (‘The Temperature’) does not give a very full picture because bees, being solid, do gain warmth from the sun’s radiance. This is easy to see when bees fly on sunny cold days, and perhaps not too difficult to measure. (With my non-scientific background, I imagine one could record the temperature of a bee held in sunshine and compare that temperature to the air temperature.)

    There are references to ‘efn’ below your weather station photo. Somehow I don’t think you’re speaking about extra-floral nectaries!

    Thanks as always for the post. And keep up the good work of maintaining so much contact with your audience individually. A huge, and possibly unique achievement! Hope you’re having a pleasant spring.

    1. David Post author

      Hi Archie

      You’re absolutely right that a bee flying at 10°C isn’t at 10°C, and that an air temperature of 10°C on a sunny day can actually feel a whole lot warmer. However I’ve tried to keep things simple … and that’s not because we don’t have any sunshine up here 😉

      The [efn] things are embedded codes I missed in my bleary-eyed 2.15am session last night as I tried to finish things off. Many thanks for spotting them – now corrected. In preparation for some other projects I’ve recently changed the way I write posts and it’s no longer WYSIWYG, but it’s much faster and more flexible.

      April started cold, probably like everywhere else. However, things have picked up and the last few days have been stunning. The bees are doing great and I’m really looking forward to the season ahead. I’m off to bankrupt myself at Thorne’s on Monday collecting all the things I should have got during the winter 🙁


  4. Ivan Marples

    Thank you for another informative and informed post

    Another geographical feature relevant to beekeeping and seasonal starts and finishes, and possibly gaps, is altitude

    My apiary is inland from Edinburgh and 230m up, and what I see beginning to flower in the city will bud chez moi a couple of weeks later. Looking at the spring migrant bird patterns in the BTO link, we can expect swallow and house martin to find accommodation in Shetland well before here

    Daily temperatures are lower up the hill, so my bees may stay indoors for more of the morning than those nearer to sea level

    I suspect, but have no data, that the June gap is compressed here, possibly to non-existence, between the late spring and early autumn. Do you have June gap data according to latitude and altitude?

    1. David Post author

      Hello Ivan

      You’re right … altitude only got a passing mention in the sentence containing the word continentality. Perhaps I should have expanded on it?

      In your situation not only is altitude a factor but the elevated temperatures within the city – the urban heat island – will also exacerbate the difference. I’ve mentioned urban heat islands (in passing) when I covered urban beekeeping and waggle dance analysis of foraging distances in rural and urban settings.

      The June gap appears to be a moveable feast (or quite the opposite). Some years in Fife (or previously in the Midlands) it was really noticeable. The OSR finished and there was nothing. In other years it seemed to be non-existent … and I don’t really know why, but assume it was due to different strains of OSR flowering at different times, varied rainfall changing nectar availability in other forage, temperature and just about everything else! I’m not aware of any (non-anecdotal) analysis of the June gap in different years or different locations (altitude or latitude).


  5. Reto

    Just a PSA, changed the way the present the weather a while ago when IBM took over and the information is nowhere near as accurate as it used to be. At least at my location. Sites that actually take local, personal weather-stations into account and calculate the weather for that specific areas are preferable, IMHO.

    Another useful site for “bigger picture” weather information is

    1. David Post author

      Many thanks Reto

      I wasn’t familiar with so have had a look and they’ve got some useful graphics to display the data. For example, they allow comparisons between locations and you can download the graphics in PNG or SVG format, which is very useful.

      The Thurso and Penzance average high and low temperatures could have been better presented like this:

      Weatherspark graphic

      Looking at the data sources they use – at least for these two locations – it appears to be largely observations from ‘local’ airports, and not from PWS’s in the area. I can’t comment on the accuracy obviously. Of the sites I mentioned, I prefer, largely because of their presentation of windspeed and isobars in some of their graphics.

      It looks as though is ‘rich’ in adverts going by the huge amounts of whitespace on my browser (all the ads are blocked using a network-wide ad blocker) and their charges for the underlying data, at least some of which (from airports) is often freely available, are not inexpensive at £75/month. I’m happy to use the graphics (and will) and provide attribution, but I’ll not be subscribing 😉


      1. Reto

        I think windy let’s you connect a PWS to their site. I do not know if it will make it into their weather model though.

        From my experience, any site that displays “long term historical data” will rely on airports or government sources for that data, because they have been around longer and are more stable than PWS.

        1. David Post author

          Hi Reto

          Yes, there’s an API for Windy that you can register for and upload data. I’m not sure if the data makes it into their model, but you can access the recent data from uploaded PWS’s, though not is a very usable format. For my beekeeping I usually want tabulated data and so often the best way to access this is to go to the individual website (if there is one), rather than one of these weather websites. For my apiaries in Fife, on the east coast, there’s an excellent PWS just a couple of miles away which I’ve regularly used to predict the best time for oxalic acid treatments, or the likelihood of my queens getting mated.


  6. ian Robinson

    Another very interesting article thanks. My latitude, longitude and altitude are fixed but this year I have noticed an additional variable which is working with the warmer weather to influence colonies. I am surrounded by several hundred acres of oil seed rape! It came into flower during the warmer spell in March and is still gong strong. Supers are bulging and colonies are strong and I expect an early swarming prep. With crop rotation though there will probably be very little oil seed rape close by next year whatever the weather.

    1. David Post author

      Hello Ian

      OSR gives colonies a huge boost early in the season. As long as the weather is warm enough for the bees to forage they always do really well on the bonanza of pollen and nectar that OSR provides. My Fife bees usually have access to it (though the acreage planted this year is significantly reduced) but those on the west coast have to make do with willow and other tree pollen/nectar. Unsurprisingly those on the east coast are well ahead and I’m likely to start queen rearing in the next ten days. In contrast, it’ll be the beginning of June before I can do much with the bees on the west coast (which were only inspected for the first time yesterday).

      Watch out for the colonies getting grumpy when the OSR ‘goes over’.


  7. Chris Birkett

    I am a newbie to bee keeping, I’m in the “winterless north” of the North island of NZ. Our first colony has just made it successfully through its first winter in a top bar hive. The weather is starting to pick up and over the past 2 weeks we have had a couple of swarms, both of which we managed to catch. My partner found your blog when looking for information. We may have made the old hive queen less as I inadvertently nipped out all the queen cells I could see. Having read some of your blog entries it looks like it is now a waiting game to look for eggs in the old hive or borrow a frame of fresh eggs from the first re hived swarm.

    1. David Post author

      Hello Chris

      If your top bar hive is the one that swarmed and you’ve then gone through and knocked back the queen cells it’s unlikely that there will be any eggs appearing in it. The colony usually swarms when the first queen cells are sealed … leaving behind some developing queens and rapidly ageing larvae. The last eggs will be those laid by the queen that left with the swarm, and they’ll be larvae 3 days after the swarm disappeared. Don’t leave the colony too long. It will do no harm to offer it a frame of eggs … if they draw new queen cells they’re terminally queenless. If they don’t – and you can tell within 2-3 days – then there’s a queen scuttling around in there somewhere and you can then safely wait for her to get mated and start laying.

      Wet, windy and very autumnal here … so I’m envious of you starting the new season. It’ll be about 5-6 months before I open another hive 🙁



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