Many parts of the UK are sweltering in what could be a mini-heatwave from today - and as temperatures in England could reach the highest of the year this weekend.
After weeks of wet and humid weather, the hot spell is being driven by a blast of warm air coming in from the Azores in the North Atlantic, forecasters say.
The mini-heatwave, defined as a period of three days or more above a certain threshold, is due to last until Monday - the day when the last of the COVID-19 restrictions are due to be lifted.
London and the South East can expect highs of 29C (84.2F) today with temperatures rising to between 31C (87.8F) and 32C (89.6F) on Sunday, according to the Met Office.
Areas further north, including Hull and Newcastle, are expected to reach the mid to high 20s as the weekend progresses with temperatures building day-on-day.
The hottest day of the year so far was 29.7C (85.5F) recorded at Teddington in southwest London on 14 June.
But we are still a long way away from record temperatures for the time of year - 38.7C (101.7F) was recorded at Cambridge Botanical Gardens on 25 July 2019.
Met Office meteorologist Simon Partridge said the weather may take people by surprise "because so far this summer has not been that great".
"Temperatures have generally been below average for quite a while - it's the difference in temperature in such a short space of time that is the most noticeable," he said.
"But it will affect most of the UK and that is a little bit more unusual - Scotland and Northern Ireland just got their warmest day of the year.
"Northern Ireland might get closer to its highest-ever temperature, which to be fair is only just above 30C (86F)."
But a mini-heatwave is definitely on the cards, the Met Office said.
For London and the South East to record a heatwave, temperatures must exceed 28C (82.4F) for at least three days, while this drops to 27C (80.6F) in the Midlands and 26C (78.8F) in the South West.
In Northern Ireland, Scotland, Wales, Devon and Cornwall and the North East it is 25C (77F).
The change in weather has prompted health officials and vets to issue warnings about the dangers of extreme heat.
Public Health England advised people to look out for those who may struggle to keep cool and hydrated, such as older people and those who live alone.
Emergency animal care provider Vets Now also warned rising temperatures could increase the risk of heat stroke in dogs.
The warnings come after a week of flash flooding in the southeast of England, causing disruption to transport in London.