It's been the hottest day of the year so far - and people have been taking to social media to share their feelings about the heat.
More than 25,000 people tweeted the term #heatwave on Monday afternoon, making it the top Twitter trending topic in the UK.
Forecasters are warning that some places in the UK will get close to 30C this week.
Very high levels of pollen and UV mean those with hay fever are in for a difficult time.
BBC Weather presenter Matt Taylor said: "Near perfect summer weather is here to stay throughout this week for many.
"Some parts of the UK could also see their warmest June conditions in decades, others one of their driest Junes on record."
BBC Weather presenter Tomasz Schafernaker said: "The hot weather will last all week long.
"Today has been the hottest day of the year, but we can't confirm if 30C has been broken yet."
It has become a bit of a British tradition to tweet a picture of your pet in hot weather.
Keeping cool... #heatwave— Marie (@pintsize73) June 25, 2018
A hot one for us here in the UK 🔥 Wishing everyone a great start to this new week 😊💞 Hoping it's one filled with smiles and happiness for you all 💗 Love and hugs
Image via AuntSamantha #Imgur pic.twitter.com/g4xAoxtVcQ
One Instagram user joined in by sharing a picture of their cat keeping cool under an umbrella.
It’s very hot here today! Usually too hot for a fluffy kitty like me to venture outside, but my hooman is doing her best to keep me cool so I can help her with work! 😻😎☀️🐾 • • • • #britishshorthair #britishblue #britishlonghair #cats #catstagram #catoftheday #catsofinstagram #kittensofinstagram #heatwave #mondaymotivation #keepcool #stayhydrated
Eleanor Hayward tweeted this picture of deer taking a dip in London.
Many people are posting pictures of their ice creams.
Rain to douse the garden is likely to be in short supply, with some people using their hosepipes in anticipation of a possible ban.
hosepipe up and running before the hosepipe ban comes in as it surely will! pic.twitter.com/UQb17FFKdq— mad but not bad (@kevinbaxter10) June 25, 2018
Alexandra Heys tweeted pictures of her and fellow staff at a Gloucestershire hospital keeping people hydrated.
Liam Smith joked about the hot weather meaning something different now that his focus is on domestic tasks.
A few years ago, a #heatwave was a chance to go out day drinking and eating ice creams all day.— Liam Smith (@LiamS29) June 25, 2018
Now, I’m excited about how much washing I’m going to get dried. ☀️👕👚👖👗🔥🔥🔥
However, not everyone in the UK was putting on the sun cream just yet. Shetland Library reminded the BBC that some places have, in fact, been quite chilly.
Dear @bbcweather, we feel that you have perhaps forgotten about us with all the #heatwave excitement?Could someone send a little #scorchio our way? 😢— Shetland Library (@ShetlandLibrary) June 25, 2018
Yours, in a chilly sort of way, @ShetlandLibrary xxx pic.twitter.com/Ybg8fV3MIO
By Victoria Park, BBC UGC & Social News