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July weather

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In winter one always pictures July as a month of blazing hot sunshine, but the reality is often a lot more ambiguous. The month often has quite changeable weather, with westerlies dominating. The old Flanders and Swan song sums things up pretty well: “In July the sun is hot: is it shining? No, it’s not!” Or as Jane Austen perceptively puts it in one of her letters (no 86): “July begins unpleasantly with us, cold and showery, but it is often a baddish month.”

By contrast, if the Azores High gets established, we can have a heatwave. You can see this large area of high pressure at the bottom left-hand corner of the weather map. If it drifts up over the UK or France, it brings air in from the south. This makes July the second of two months (the other being June) which typically see the hottest temperatures of the summer. If there is going to be a heatwave, it is very likely to happen in this month.

Even when the Azores High is kept out, it is not always a disaster. While the north of the UK has cool, wet weather, the south is often near the boundary between the two systems. This means that while the weather is changeable, it is relatively dry and benign. At such times hot sunshine, some clouds and just the occasional shower make for very typical English summer weather.

Years when it was hot

The most recent hot July was 2022, when ten days of hot sunshine mid month culminated in temperatures of 37 degrees on the 18th and a record 40 degrees on the 19th, these two days being the result of a plume of air from the continent where temperatures were widely into the mid 40s. It was also the driest July in the south east since records began in 1836, though in fact there were small amounts of rain on the first two days of the month and on three days just after the heatwave peaked. Even apart from these it was not wall to wall sunshine: the first week and the last ten days of the month were actually fairly cloudy. But the sun then returned for two weeks in August, leaving the countryside totally brown, trees shedding leaves and rivers at a low ebb.

July 2022 was seen as confirmation that global warming was definitely happening, but the same fears had already been raised in 2006 and 2018. In the latter year a heatwave that had started with ten days of sunshine in late June carried on into July, with temperatures at or near 30 degrees. Coming on the heels of a dry May and June, this turned the countryside parched and brown. There was some sultry cloud from 8-13 July, with temperatures dipping to the mid 20s, and four cloudy days culminating in rain (the first for 23 days) spreading up from the continent to Kent, East Sussex and the Chilterns on the 20th. But hot sun then returned, with temperatures rocketing up to 35 degrees on the 26th. A thundery breakdown took place the following day, bringing substantial rain, and there was further rain on the 29th and 31st, but the next six days were again sunny with temperatures up to 33 degrees. The heatwave finally ended on 8 August, with heavy rain on the following two days.

In 2006, meanwhile - at the time the hottest July on record - there were successive waves of heat building to an intensely sticky climax with temperatures of 37 degrees. Grey showery weather tried to unsuccessfully to break through from the 5th to the 10th, but there were no more than a few spots of rain. The grass, already parched by a dry June, shrivelled completely, and trees and shrubs started to wilt.

By contrast to these three years, the July 2013 heatwave was seen a welcome tonic after a very cold and grey winter and what seemed like years of disappointing summers. It started on the 5th with five days of sunshine and temperatures in the high 20s, and after a brief slightly cooler interlude resumed on the 13th with temperatures of 30-31 degrees. The hottest days were the 18th, at 32 degrees, and the 22nd, at 33.5 degrees, which was followed by a sultry 23 degree night. Thereafter the weather was slightly more mixed, with a few showers but also plenty of sunshine, until proper rain came on the last two days of the month.

In 2019 highs dominated for most of the month, with slow moving lows to the north west of the UK. This brought at least some sunshine to half the days in the month, though there were only seven days of unbroken sunshine. Otherwise there was a fair bit of sultry cloud, with rain only occurring on four days, once as overnight thunderstorms. The month included two short heatwaves. One was from 4 to 6 July when the high was right over the UK, bringing temperatures of 25 degrees. The other was from 22 to 25 July when the high was centred over Denmark, bringing air straight up from the Sahara. Temperatures rose to 33 degrees on the 23rd and 24th and 38 degrees on the 25th, when an all-time UK record of 38.7 degrees was recorded in Cambridge. Midnight temperatures in this period were also a record 25 degrees in London.

In other years, westerlies predominate but the weather is relatively benign. This was true in 2014, which saw a mainly sunny July following on from a largely pleasant June. Rain was scattered throughout the month but it nearly always occurred at night. Otherwise sun and cloud predominated with temperatures in the low 20s and a mini heatwave (albeit with some thunderstorms) from the 17th to 18th, when the thermometer pushed up to 30 degrees. The month then ended with ten days of near total sunshine (barring one night's rain on the 27th) with temperatures in the high twenties that again peaked at 30 degrees on the 23rd and 24th.

In 2016, despite westerlies being in charge most of the month, only two days - 11-12 July - saw heavy showers, while seven others had minor showers. 27 days had at least some sunshine, and six of those had full sun, three in a heatwave caused by a continental high which lasted from 18-20 July and brought temperatures of 33 degrees. The 16th, 17th and 23rd also saw temperatures rise to 26-27 degrees: otherwise daytime highs were around the 20-22 degree mark.

In July 2010, the Azores High lurked just to the south west of the UK, leaving us technically in westerly lows, but producing minimal rain. There was quite a lot of cloud, and temperatures remained in the low twenties, with three brief forays into high twenties (up to 30 degrees on the 10th). The countryside remained very brown and desiccated after a dry spring and early summer.

Years with more rain

Years when July was rather wetter include 2023, when the whole month saw changeable weather due to lows from the north west. But this was a welcome contrast to a very dry June and second half to May, and to much of the rest of Europe, which was seeing temperatures into the high 40s - widely seen as evidence of global warming ramping up. There was only one full sun day - the 3rd, when temperatures reached 30 degrees - and two more that were fairly sunny. But the month was by no means a wash-out. While an astonishing 18 days saw some rain (with an intense storm, with 50 mph winds on the 15th), 20 also saw some sunshine, and temperatures mostly peaked at 19-24 degrees. It was in many ways classic English summer weather.

In 2011 high and low pressure alternated, with regular showers throughout the month, and heavier rain from the 16th to the 23rd. There was a good deal of sunshine mixed in, with temperatures in the 18-24 degree range, but until the last two days of the month it was never sunny all day: cloud always bubbled up in the afternoon.

The first three weeks of July 2012 saw heavy showers, frequent grey skies and disappointing temperatures (sometimes only 17 degrees by day). This followed an extremely wet spring and early summer, which had seen double the normal April and June rainfall, and just one week of sunshine in May. But on the 21st high pressure finally established itself, and there was a week of blue skies, with temperatures of up to 30 degrees - just in time for the start of the London Olympics.

In 2009, following a heatwave in late June, static lows sat over the north of the country for much of July, bringing heavy showers and strong winds across the south at times, but good sunny intervals and reasonable temperatures (20-24 degrees). Three Saturdays and one Sunday were broadly sunny.

July 2007 was dominated by a succession of Atlantic fronts that brought heavy flooding to Gloucestershire and Oxfordshire, making national headlines. But it was not such a terrible month in the south east, with four sunny weekends, and good amounts of sun on other days. Coming after a wet May and June, it seemed as if there would be no summer at all that year. But the weather finally relented on 28th, when a two week heatwave set in, with temperatures of up to 30 degrees.

In 2020 the Azores High tried several times to establish itself, but only succeeded for three days from the 20th to 22nd and then from the 29th onwards. Otherwise, the month was changeable, cloudy and showery, with rain on 13 days, though some sunshine on 14 days. The 29th saw the start of a heatwave which lasted until 14 August, however, with the 31st seeing temperature rise to 37 degrees.

In 2015 the month started with a heatwave - on 1 July temperatures equalled and slightly exceeded the 2006 record of 37 degrees and it was still 27 degrees at midnight: it then remained sunny with temperatures in the high twenties for the next three days. But thereafter there were lows centred over Scotland which brought more changeable weather. There were wet periods - especially from the 12th to the 15th and towards the end of the month (3.5cm of rain fell on 24 July and temperatures were just 13 degrees by day) - but sunny or fine days were in the majority, with temperatures in the low 20s, albeit often tempered with a strong breeze.

July 2017 also started with a heatwave, with temperatures getting up to 32 degrees, though only four of the first nine days had full sunshine. Westerlies then set in from 10 July onwards, with a breezy mix of cloud and sun and temperatures in the low twenties or (sometimes) high teens. Thirteen days in this last two thirds of the month - nine of them in the last eleven days - had some rain, with thunderstorms and heavy showers at times.

In the famously hot dry spring and summer of 2003, July was sunny until the 17th, but thereafter was cloudier and cooler, with heavy rain on the 25th and the 26th. Sunshine then resumed on the 27th (with one last day of rain on the 29th), and the whole rest of the summer was hot and sunny.

In 2021 the month started with eleven days of westerly lows, bringing weather that was fairly cloudy and showery, but with some sunshine. High pressure then set in from the 13th, with a week of hot sunshine starting on the 16th. Temperatures soared to 31.6 degrees on the 18th and stayed above 30 degrees for the next three days. This heatwave ended in a classic thundery breakdown on the 24th and 25th, caused by a low coming up from the continent, with some flooding in London. This low proved slow-moving and caused heavy showers for the rest of the month.

So easy to forget

Needless to say after three days of either type of weather, everyone forgets the other ever existed. When the weather is grey, the complaint is that that we are having no summer at all this year, and the newspapers have gleeful stories about UK holidaymakers caught in the downpours. When the sun shines, the tabloids trumpet that it is hotter than Rome, Morocco or Acapulco. Hot weather can also lead to “capitulation” - a weariness with the heat, insect bites and the endless applications of suntan cream that makes you secretly long for autumn.

Even on cool days in July one rarely needs a second layer. Night time temperatures are rarely much below the 12-15 degree range, and you can often get away with short sleeved shirts even after dark. 27 July 2005, for example, a day of heavy rain, was declared “the coldest July day in London for 25 years”. But even so, a waterproof on top of a short sleeved shirt was still more than adequate right into the evening. Meanwhile, during heatwaves night time temperatures can be really oppressive – generally anything above 17 degrees produces this effect, while 20 degrees feels very sticky.

July starts with sunset at 9.20pm, its maximum extent, and for the first ten days or so of the month, the dusk also seems to get no earlier, as if the long evenings will last forever. Towards the end of the month one starts to notice the shortening days ever so slightly, however. Imperceptibly official lighting up times have crept back 9.20pm to 8.50pm. For the moment, you only notice this because it is pitch black at 9.30 pm, whereas a few weeks ago it there was light in the sky until after 10pm, however. Early risers will also notice that the sun comes up at 5.20am by the end of the month, as opposed to 4.50am at the beginning of it.

By early July the sea off the south coast is at last warm enough to swim in comfortably (16 degrees at the start of the month, 18 degrees by its end), though more enthusiastic swimmers have been taking dips in it since mid June (or even earlier). One sometimes rushes to the coast on a hot sunny day to find the weather there cool and breezy, however, or even overcast: temperatures on the coast can be up to five degrees lower than those inland.

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© Peter Conway 2006-2023 • All Rights Reserved

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