In the middle of summer 2019, very warm air surged up from Europe and the UK saw a maximum temperature of 38.7C (101.66F) on the 25th July. The hottest day ever in the UK, with the top temperature being recorded at Cambridge Botanic Gardens. After that spell of intense heat, there were dramatic thunderstorms over parts of Britain.
July 2019 wasn’t hot overall, it was slightly warmer than average across the UK. It was 2018 when the UK endured a lengthy hot and dry spell with average temperatures being several degrees higher, particularly for England and Wales in July.
Before that, the UK record was 38.5C (101.3F) from the 10th August 2003, recorded at Faversham in Kent and this remains the hottest August day for the UK. August 2003 was hotter and much drier than average.
Summer 2020 has only just got going with heat and sunshine, after a mixed and unsettled June and July, following the warm, dry and sunny conditions of COVID lockdown in spring 2020. The UK doesn’t often see temperatures over 35C but saw the 3rd hottest UK day on record on 31st July 2020 with 37.8C (100F) and has recorded 36.4C on the 7th August.
38.7°C - 25 July 2019 38.5°C - 10 Aug 2003 37.8°C – 31 July 2020 37.1°C - 3 Aug 1990 36.7°C - 1 Jul 2015 36.7°C - 9 Aug 1911 36.6°C - 2 Aug 1990 36.5°C - 19 Jul 2006 36.4°C – 7 Aug 2020 36.4°C - 6 Aug 2003
The last day of July 2020 produced an intense short-lived spike in air temperature. 37.8C was recorded at London Heathrow and 37.4C at Kew Gardens also in west London. The tarmacked runways of Heathrow airport are sometimes questioned, that it isn’t a representative temperature of what people are experiencing. However, the corroboration with Kew Gardens observations shows that Greater London is getting that hot.
As temperatures records continue to fall around the world, the idea that the UK could reach 40C seems more of a ‘when’ than an ‘if’.
What was unusual about the 31st July was that there was little build-up with the temperatures. Usually the heat increases over a few days, with some sultry nights, the concrete in the city buildings holds onto that warmth and a top temperature is worked up to. This one just appeared suddenly, although Surrey and Lincolnshire did record 3 hot days in a row.
A week later August 2020 produced another hot spell but a longer one. Official heatwave conditions for more of England and Wales, particularly SE and eastern England. “Temperatures reaching or passing a location based threshold for three days or more.”
On Friday 7th August, London Heathrow and Kew Gardens reached 36.4C (97.5F) becoming the 9th hottest day on record for the UK. Medium level cloud just reached Greater London later in the afternoon stopping any further rise. Overnight, the highest minimum air temperature was 22.3C at Landon Bay in Kent. So, it didn’t get any“cooler” than 22C during the night, how was sleeping in that? The record for the highest minimum temperature is 23.9C on 3rd August 1990 in Brighton. These are UK “Tropical Nights”. The term describes days when the temperature does not fall under 20.0° C during the night-time. It doesn’t happen that often and is localised but the UK Met Office began tracking them in 2018 as extra data for climate research.
Public Health England issued a Heat-Heath warning which requires social and healthcare services to target specific actions at high-risk groups. This was proper summer heat.
Advice in hot weather - Look out for others, especially older people, young children and babies and those with underlying health conditions. Close curtains on rooms that face the sun to keep indoor spaces cooler and remember it may be cooler outdoors than indoors. Drink plenty of fluids and avoid excess alcohol, dress appropriately for the weather and slow down when it is hot.
Hot weather can be welcomed and enjoyed by many people but for others, it can be overwhelming or cause extra stress to pre-existing health conditions. Air pollution episodes can also occur in hot weather with ozone levels rising in strong sunshine heightening risk for people with heart and lung conditions. Pollen levels can be high and the relentless heat with perhaps lack of sleep can affect people’s mood. However, for others, the warmth and sunshine generate a feeling of wellbeing and happiness with more opportunities to be outdoors. Here in the UK, the extreme heat doesn’t tend to last for too long, often ending with a thundery breakdown. Thunderstorms are forecast for the start of next week as the heat continues in the south.