ritons are warned of widespread disruption as temperatures appear to reach a dangerously high peak in the coming days.
Forecasters believe there is a 30% chance that the mercury will break the current UK record of 38.7C, set in Cambridge in 2019 as temperatures continue to rise over the weekend and into the next week.
An “orange” warning of extreme heat affecting much of the England and Wales on Sunday and Monday says there could be life-threatening or potentially serious illness, with adverse health effects not just limited to the most vulnerable.
There could also be road closures and delays and cancellations of rail and air travel, while ambulance services in England are at the highest level of alert as hot weather issues combine with Covid absenteeism among staff and ongoing delays in transferring patients to A&E.
Wednesday, Thursday and Friday are likely to bring some rain in the north of the UK and highs of 27C or 28C – slightly cooler than Tuesday, which saw 31C in parts of South East England.
But temperatures are expected to rise again over the weekend into the mid-30s before reaching a peak on Monday, with the southeastern parts of the UK seeing them rise above 35°C and locally into the high 30s.
Forecaster Matthew Box said: “As we get there on Sunday, it looks like we could see temperatures soar into the high 20s and low 30s, but possibly a few spots reaching 34C or 35C by Sunday and probably the same on Monday.
“We could see temperatures rise to the mid or high 30s by Monday and there’s about a 30% chance we could see the UK record break, most likely right now on Monday.”
High temperatures could also persist into Tuesday.
“Looks like it’s going to be hot or very hot over the weekend and next week,” Mr Box added.
He explained that the heat wave is the result of hot air flowing into the UK from the continent.
He said: “What happens when we come into the weekend, the high pressure is centered in the east of the UK and that allows a southerly airflow to drag up, the very warm air that is currently over France, and drag it northwards to the UK at the weekend, maybe more on Sunday and Monday.”
Heat waves have been made hotter, longer and more frequent by climate change, and experts have warned of the need to adapt homes and towns in the UK for a future of more intense summer heat.
network rail prepares to introduce speed limits to reduce the chances of rail sagging as the heat wave continues, causing delays to passenger travel and disrupting freight traffic.
London Ambulance Service urged the public to support it while the heat continues by calling 999 only in the event of a life-threatening emergency, staying hydrated and out of the sun during the hottest times of the day.
The Royal Life Saving Society UK warned people of the dangers of trying to cool off in lakes, quarries, rivers and other waterways in extremely hot weather.