Where are the hottest places in the UK?

When hot spells of weather arrive in the UK, you may have noticed that some locations seem to more often record the highest temperatures.

So where are the UK's hotspots? What is so special about these sites that make them more likely to see the hottest weather?

If you like your weather extremely hot, then eastern England is the place to be. Eight out of ten of the UK's hottest days ever recorded were from locations in eastern England. This includes the current UK temperature record of 40.3C set on 19 July 2022 in Coningsby, Lincolnshire.

Eastern England often sees the highest temperature in the UK for a number of reasons. It is well away from the prevailing westerly winds which bring in fresher air from the Atlantic.

Its proximity to Europe helps too as any hot weather that develops over the continent can more easily spread in.

Much of eastern England is relatively low with many areas below 100m elevation. This is important, because for every 100m higher a location is, temperatures drop by 1C.

The sun's energy is more concentrated in the south of the UK than the north, this can lead to higher temperatures.

Also atmospheric pressure tends to be higher to the south of the UK, this means more sunshine and more heat.

Each day the Met Office records the location with the highest maximum temperature, with Heathrow, Kew and St James's Park seeming to often feature. These sites are all within Greater London.

These heavily built up areas with lots of concrete and asphalt heat up more quickly, and hold on to that heat much more than rural areas. The city acts as a big storage heater so overnight temperatures don't fall as far as those in the countryside which is known as the urban heat island effect.

During warm spells, temperatures will often start the day from a much higher point with the heat continuing to build through the morning and afternoon. Both daytime and night time temperatures can then climb over consecutive days during warm spells.

Four out of 12 of the UK calendar month records are set by locations in Greater London, testament to the heating power of London's urban heat island.

Santon Downham (Suffolk) is another site that seems to pop up frequently as the day's hotspot. Although some heat could easily waft here from the heat islands of London or Cambridge, there is another explanation for the high temperatures.

This area has sandy soils and these drain water very efficiently. This means a greater proportion of the sun's energy goes into heating the ground rather than evaporating water in the soil.

This warmer ground then goes on to heat the surrounding air, making it a UK hotspot.

Usk in Monmouthshire is a frequent Wales hotspot. This lowland site is sheltered from the prevailing westerly winds by the mountains of the Brecon Beacons with temperatures sometimes boosted by the foehn effect.

During heatwaves, hot air from the Midlands can easily drift here too. Meanwhile, if the winds are blowing from the east over the Cambrian mountains or Eryri (Snowdonia), watch out for Trawscoed (Ceredigion) or Porthmadog (Gwynedd) also making the hotspot list.

In Northern Ireland, Castlederg (County Tyrone) often tops the list. This site is on low ground and is sandwiched between the Blue Stack Mountains to the west and the Sperrins to the east. Again this means that the foehn effect can boost temperatures here whether the winds are coming from either the west or the east.

Looking back at the list of the UK's highest calendar month temperatures for the winter months, both the December (18.7C) and January (19.9C) records are from Achfary in the northwest Scottish Highlands.

We don't get as much energy from the sun during winter, so other factors can be much more important for warmth. The Atlantic Gulf Stream boosts sea temperatures to the west of the UK, with much cooler waters forming in the North Sea.

This means western areas will often have milder winter weather with St Mary's, (Isles of Scilly) often a winter warm spot

The foehn effect (which gives Usk its summer hotspot status) has a few different causes but can be really important for boosting winter temperatures too. Warm moist air rises up over mountains, with rain on the windward slopes. The air cools as it rises. Drier air descends on the other side of the mountain, and this drier air warms at a greater rate. This can lead to much warmer air forming to the lee of mountains.

Mountains can also block cloud from moving in, so the lee side of the mountain can be much sunnier, this can also boost temperatures. Finally, winds moving over the mountains can mix down different airmasses, causing warmer air to arrive in valley bottoms.

Locations like Altnaharra, Tulloch Bridge, Lossiemouth and Aboyne are frequently winter warm spots due to the foehn effect.