While Southern and Southeastern England has taken the majority of summer’s heat. The most recent installment of hot weather however was shared more widely and boy was it not an impressive spell, especially for Scotland as well as Ireland, Northern Ireland up into Scandinavia including Iceland.
Through 10th July and before the arrival of the season’s 3rd heatwave, days above 25C has been routine in the London and SE region, a pattern of repetition courtesy of an MJO largely focused between east Indian Ocean-Maritime Continent-West Pacific with sinking over the Americas and Atlantic. This coupled with dry ground has likely reinforced a highly anomalous Icelandic trough/Europe ridge set up with battle in between.
June was England’s warmest and UK’s 2nd. Multiple days at or above 30C in S and E England with a peak of 33.2C at Charlwood, Surrey on the 21st. Warmest night being 20.5C at Nettlecomb, Somerset on the same day.
There was a brief 1-2 day heat spike for Ireland, NI and Scotland with 29.5C at Castlederg, Tyrone and 29.1C at Grangemouth. Orkney observed it’s wettest June while Cumbria it’s 4th wettest while less than half the normal rain fell in east and southeast England.
On July 1st, a temperature of 35.8C was achieved at Faversham, Kent.
The 3rd heatwave occurred from a hemispheric chain reaction initiated over the Indian Ocean/Himalaya/Maritime Continent region thanks to large scale upward motion triggering an eastward propagating Rossby-wave which led to an anticyclonic wave break from Atlantic into Europe.
…graphic…
This buckling and amplification of the Atlantic-Europe pattern forced a steep build-up of pressure and consequential ‘adiabatic compressional heating’ process over the UK.
Rather than a surge or plume originating over North Africa, the air mass in fact had it’s origins within warm, dry upper levels of open mid-Atlantic Ocean…. this ‘home grown’ heating process, generating a notable hot spell especially in the North (though setting off another round of 30C+ days in the South) was most likely enhanced by dry air which was dried out further by compression through subsidence as well as dry ground and warmer than average surrounding seas.
Temps widely 10-12, locally 14C above average. A difficult margin to achieve in the height of summer.
All UK nations and Ireland exceeded 30C together for the first time this summer.
While the highest reading of this 3rd heatwave of summer came in at 33.1C in SE Wales, it’s the rarity of the readings up in Scotland NORTH of the Central Belt which is particularly noteworthy.
Ireland witnessed at least 4 sites at or above 30C with Mt Dillon warmest at 31.1C.
UK maximums for 12th July.
5 new all-time records we’re set in Highland Scotland on Saturday 12th July, 2025.
32.2C Aviemore (31.3C, 27/6/18)
31.2C Achnagart (30.6C, 8/8/03)
31.2C Kinlochewe (31.1C, 19/7/06)
29.9C Altnaharra (29.4C set 19/7/06)
29.0C Loch Glascarnoch (28.0C, 27/6/95)
Another hot day followed on the 13th throughout the UK and Ireland. a rare 2nd day in a row exceeding 30C at Aviemore and Achnagart, Highland.
The new Aviemore record of 32.2C is said to be a new Highland regional record exceeding the previous of 32.1C set on 1st August, 1995 at Onich, Lochaber.
However, Forres, Moray recorded 32.5C back in August 2003 which appears to be Northern Scotland’s highest temperature. Nearby Gordon Castle, Moray recorded 32.2C in September 1906.
Unusually Large Diurnal Swing!
As well as the impressive daytime maximums, we observed some unusually large diurnal swings, particularly for a midsummer heatwave.
At Aboyne, Aberdeenshire, a high of 30.8C on the 12th was followed by a low of 5.5C on the morning of the 13th followed by a high of 27.5C the same afternoon. A full 25.3C swing in 12 hours.
At Altnaharra the morning of the 12th started with a low of 7.1C rising to an afternoon record high of 29.9C (22.8C swing). The following morning, the thermometer fell back to 6.7C (23.2C) before returning to 27.4C by afternoon.
Other examples…
Loch Glascarnoch 29C to 7.2C (21.8C)
Aviemore 32.2C to 11.9C (20.3C)
Low humidity and dew points aided these big swings but it’s more typically found during spring and autumn.
By the 14-15th a system drifted in off the Atlantic bringing a steady drop in temperature along with heavy rain and showers. Further north and it was less rain and cloud and more sun with a continuation of low to mid-20s throughout the following workweek. This is by far the best and most sustained warmth of summer for many north of the M8 corridor.
Record Heat Lifts North!
As the fresher air moved in, the hot air didn’t just disappear, it headed north bringing warmth throughout Orkney, Shetland, Faroes and some major heat to Norway, Sweden, Finland and Iceland.
Not often do we see widespread 20s throughout Shetland.
15C+ at 850mb widely over Scandinavia.
850mb temp anomaly Friday 18th.
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Friday 18th July, temperatures reached 31.1C in Banak, Norway at 70N, well within the Arctic Circle.
While the 31.1C at Banak is impressive, 32C was reached here in 2018 and an all-time high of 32.5C was recorded in 2022, considered highest temperature recorded within the Arctic Circle of Europe.
FEATURED IMAGE CREDIT: Loch Morlich Watersports
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