When will London's heatwave end? Thunderstorms inbound

Sunday was officially the hottest day of the year after temperatures reached a whopping 31.6C in Heathrow in south London, smashing the previous record of 29.7 recorded in Teddington.

Londoners have been enjoying gorgeous weather as they celebrated Freedom Day on Monday, and has been too hot even for some with the mercury almost sticking to 27C and above during the daytime.

The Met Office even issued its first ever "amber extreme heat warning" as parts of the UK reached a sizzling 33C, with the warning in place until Thursday.

But this hot spell has to end at some point, and it appears that end isn't too far away.

Thunderstorms are already predicted for later tonight (July 20) at around 7pm and 8pm, and a yellow weather warning for thunderstorms has been issued.

This is not the end of the hot weather, however, with Wednesday set to be another scorcher at 30C by 3pm, according to the Met Office.

Thursday won't quite reach the same heights with a top predicted temperature of 26C and some clouds, but will largely maintain the status quo.

Friday is where things start to change, with a hot daytime (temperatures peaking at 22C) changing to cloudy and slightly cooler by the early evening.

And Saturday will bring with it "heavy showers" throughout the day the Met Office forecasts for the capital, with a 70% chance of precipitation throughout the day.

• Flood alert in place across south east London as thunderstorms forecast

Sunday's forecast shows heavy storms on the horizon, with lightning and thunder set to hit London at 10am, 4pm and 7pm as heavy rain and thunderstorms bring the heatwave crashing down.

Despite the heavy downpour, the Met Office still predicts temperatures of up to 23C during the weekend.

Following the heatwave warning issued earlier in the week, Met Office forecaster Dan Stroud told the PA news agency: "This type of warning is issued when temperatures are unusually warm for a particular location, with the threshold different in certain areas of the country.

"Really it's to raise awareness that extreme heat can have an impact on things like your wellbeing, power supply and transport so people should take action.

Public Health England (PHE) also issued a heat-health alert, warning members of the public to take measures to stay cool and look out for vulnerable people.

Amber and red warnings can now be issued to inform the public of potential widespread disruption and adverse health effects.

Forecasters said the amber warning comes as the forecast continues to signal for unusually high temperatures for western areas in particular, as well as continuing high nightime temperatures creating potential impacts for health.

Extreme heat can have health consequences, especially for those who are particularly vulnerable, and it can impact infrastructure, including transport and energy, as well as the wider business community.

Dr Owen Landeg, Scientific and Technical Lead at PHE, said: "Everybody can be affected by high temperatures and most people are aware of good health advice for coping with hot weather.

"However, it's important to keep checking on those who are most vulnerable such as older people and those with heart or lung conditions.

"As we experience the first hot weather episode of the year, it's important for everyone to remember to adapt their behaviours. This is particularly important during the pandemic with many people self-isolating."

Met Office chief operational meteorologist Steven Ramsdale said: "The high temperatures are going to continue through a large part of this week.

"Many areas will continue to reach heatwave thresholds but the amber extreme heat warning focusses on western areas where the most unusually high temperatures are likely to persist.

"There's a continuing risk of isolated thundery downpours late in the afternoons but most areas will stay dry until later in the week."

"Temperatures should begin to fall for most areas heading into the weekend, with some more unsettled conditions looking to develop."