A warning has been issued by the Met Office over fears that the expected heatwave will have a significant impact on health.
This weekend is set to bring the hottest day of the year so far, with weather experts predicting temperatures will reach a sizzling 31C (87.8F) on Saturday.
The mercury will begin to creep up to the high-20s over Friday before spiking at the record. The continued hot spell shows no sign of ending as temperatures settle around the mid-20s well into next week.
A Level 2 Heat Health Alert has been issued by the Met Office for parts of England.
A spokesman for Public Health England (PHE) said: "Level 2 alerts are triggered as soon as the Met Office forecasts that there is a 60% chance of temperatures being high enough on at least two consecutive days to have a significant effect on health.
"This will normally happen two to three days before a heatwave is expected to occur. As most deaths occur in the first two days, this is an important stage at which to ensure readiness and swift action to reduce harm from a potential heatwave."
The areas affected by the alert are Yorkshire and the Humber, East Midlands, East of England, south-east England, London and south-west England. The Met Office alert warned of heatwave conditions on Friday and Saturday. "Heatwaves can be dangerous, especially for the very young, very old or those with chronic diseases," the alert said.
Dr Angie Bone, head of the PHE's Heatwave Plan, said: "Everyone can enjoy the sun safely by keeping out of the heat at the hottest time of the day, avoiding sunburn and staying hydrated with plenty of cool drinks. The elderly and those with long-term illnesses are particularly vulnerable to the effects of very hot weather, so it's important to look out for them and keep indoor areas as cool as possible."
The RAC said more than 11 million motorists were planning to hit the road this weekend. Popular spots include the Lake District, Devon and Cornwall, the south coast of England and Yorkshire. The RAC added that it was boosting the number of its patrol teams following a sharp rise last weekend in hot weather-related breakdowns.
Meanwhile, motorists have been urged to avoid the M5 in Devon - a popular route for holidaymakers - following an accident. The northbound carriageway is closed after a horsebox overturned near Cullompton at 1.15pm on Friday. Devon and Cornwall Police said the incident happened after the trailer, which was being towed by a Daihatsu Fourtrak vehicle, overturned in the middle lane. Two horses were injured in the incident and have been treated at the scene by a vet. A force spokesman said: "The northbound carriageway and the onslip have been closed at Junction 29. Traffic on the southbound carriageway is moving slowly. The incident is causing considerable tailbacks and drivers are urged to avoid the area if possible."