People are being urged to "stay out of the sun" for most of this week, as a heat health watch alert is issued by the Met Office.
Many people can not avoid the sun because they have to work in it. And, they need to wear work uniforms.
From pizza chef to nurse, priest to labourer, 10 UK workers told us what it is like to wear a uniform in hot weather. They also shared their top tips for keeping cool.
@emsk tweeted: "I'm a nurse and my husband is a police officer. As soon as we come in from work it's straight to the shower.
"In fact today our female staff took to filling gloves with ice and shoving them in our bras."
Nurse @Trac36Tracytots tweeted: "Haven't got any tips, full nurses uniform, no air con, still have to wear tights, no alternatives, melting."
@jadesapphirejet, tweeted: "Nurses! Uncomfortable polyester tunic's and trousers. Lace up shoes with socks. No air con in NHS wards. Rubber gloves and plastic pinnies.... you try keeping cool while doing a dressing in that get-up. #nhsuniforms
2. Customer service assistant
Seray Justice and Ro Moloney, customer service assistants for Transport for London, said they do not have many options.
"We take breaks but this doesn't help. Downstairs, on the platforms, we carry even more equipment and it's hotter.
"Last week we had no air con and the water was warm. We sometimes feel dizzy it's so hot."
Priest Jo Haine from Dorchester, Dorset, tweeted a picture of the uniform she has to wear, whatever the weather.
She said: "It's too hot for clergy robes! I'm afraid I haven't worked out how to stay cool, it's boiling in them. I just drink plenty and, if outside, try and stand in the shade."
Another priest, James Pacey, tweeted: "I'm a priest so dress all in black. Took my black cat to the vet today - he said black cats feel the heat. I said I know how they feel."
4. Pizza chef
Valentino Diesi said he tries to drink to stay cool.
"Everyday is busy and I sweat sometimes when it's busy. My pizza oven goes to 300C. So I try to take breaks when I can."
Twitter users also commented on what it is like to work as a chef in the heat.
@Food_o_Graphics tweeted: "I've seen chefs using wet towel from a freezer around the neck."
@geordiekev1uk replied: "I can vouch for that, being a chef lol."
Peter Wackett, Jake Phillips and Luke Cahalane work 10-hour shifts in the sun.
"We're here all day, sweating like pigs," said Mr Wackett.
"We don't take breaks. We have to wear these flame-proof overalls. I feel like passing out when we're shovelling and heavy lifting, especially when the sun's in my eye.
"There isn't any air con in the back of the van."
@LeicsFireRescue tweeted: "We might know a few people whose job requires them to wear protective uniform whatever the weather! We're not sure there's any way to stay cool in a fire, but hydration is key for our crews to stay fit and well - especially in this heat!"
While firefighter Scott Pearce said: "Sometimes there are no shortcuts, stay hydrated and rest in shade where possible."
7. Airfield operator
Emma Gilmartin works at Exeter Airport.
She said she is supplied with water and a choice of uniform: "Each department is also issued with sun lotion dispensers and we are regularly encouraged to re-apply.
"The company has a great sun safety awareness campaign at the start of each summer.
"Personal protective equipment includes hats with a visor for each of us. I'm really grateful to have a safety conscious employer."
8. Street kiosk manager
Peter Rowlands said the heat is stifling: "The heat comes out of the front of the fridges. I put a fan on but it's not doing much."
Antonio Manuel told the BBC: "It's so hot in my uniform. I go outside and I stand in front of the air con. I drink water and soda."
Another bartender tweeted: "I work in a pub so run around a lot. (Average 11000 steps per shift!) We have to wear black shirts and black trousers. No air con, no fans, and under a plate glass ceiling. It's affecting all of us atm. No need for toilet breaks, as we sweat out whatever we drink."
10. Police motorcyclist
Whilst @candascott described the leather uniform he needs to wear: "Police motorcyclist, leathers, boots, stab vest, motorcycle jacket helmet and gloves."