UK weather - live updates: Hottest day of the year recorded as heatwave sees Heathrow hit 35C

Here's the latest on the weather from The Independent's very own Harriet Agerholm.

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The Circle Line on the London Underground is having a bad old morning of it, terrible news for those not overly keen on losing half their body weight in sweat. Drink plenty of water today folks.

It is now officially the hottest day of the year!

The Met Office reports that Charlwood in Surrey has reached 33.9C.

Phew, what a scorcher!

Here's your confirmation

Highways England is urging drivers not to throw rubbish from their vehicles amid a surge in grass fires near busy roads.

There have been 56 fires on grass verges next to England's motorways and major A-roads over the last 10 days, the organisation reports.

Burning temperatures and the lack of rain have made verges drier than normal and many are catching fire as a result of to items being thrown from passing vehicles like glass bottles, cigarette butts and plastic.

Highways England's emergency planning officer Frank Bird said: "Smoke from roadside fires can drift across motorways posing a hazard to drivers. We've seen an increase in fires on grass verges near some of our motorways, for example on the M42 in the Midlands.

"With the land being so dry, it often only takes a small spark to take hold. We'd urge people to avoid throwing any items from vehicles at any time, but particularly in these hot conditions."

Passengers on the cross-Channel Eurotunnel services are having a bad time of it today, facing delays of up to five hours after air-conditioning units failed on trains amid the baking heat.

The English end of the Folkestone-Calais link was worst affected, with travellers forced to queue for up to 90 minutes to check in and a further three and a half hours for the next available slot, according to the operator.

A Eurotunnel spokesman said: "Due to the exceptional and prolonged temperatures, some of the air-conditioning units on board our shuttles are struggling to produce sufficient cool air.

"Our priority is customer well-being and safety so we are unable to board vehicles to these carriages."

Nurses working in Britain's busy hospitals are reporting suffering exhaustion, sickness and dizziness as a result of working long shifts in the intense heat, according to the Royal College of Nursing (RCN).

Kim Sunley, national officer at the RCN, said: "Nurses are now becoming patients themselves due to the heat.

"We have heard from one member who ended up in A&E suffering from dehydration, after working 12-hour shifts back to back in temperatures exceeding 30C.

"Others have reported exhaustion, sickness and dizziness.

"This is not acceptable. Good patient care depends on nurses and clinical support assistants being well enough to perform their jobs effectively.

"It is vital employers adapt working practices to the heat. Both patients and nurses must have easy access to water, and all healthcare staff should be able to take regular breaks, preferably somewhere cool."

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