In the North East, temperatures are set to peak at about 25C - and the thunderstorm warning applies here.
As people continue to battle through this year's enduring heatwave, many are drawing comparisons with the scorching summer of 1976.
According to the Met Office, there is a 20% chance that Friday could have the highest temperature since records began. The mercury hit 34.5C (94.1F) at Heathrow on June 21 past year.
The all-time British record is 38.5 degrees Celsius set in August 2003 near Faversham in Kent, south east England, while the highest July temperature was 36.7 deg C in 2015 at Heathrow airport.
Paul Gundersen, Chief Meteorologist at the Met Office, said: "The heatwave conditions will continue across much of England, with temperatures into the mid to high 30s Celsius in many places from the Midlands eastwards on Thursday and Friday and it's possible that we could break the all-time United Kingdom record of 38.5C if conditions all come together".
The yellow warning is in place between 2pm and 11.45pm on Friday, July 27.
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The level 3 warning, one behind a national emergency, has been issued with temperatures set to be in the high 20s this week.
Fire brigades also called for a ban on barbeques in parks, and drivers were urged not to throw rubbish following a string of grassland fires in recent weeks.
"But the heatwave has meant that in some places at least, we're back to winter conditions - in hospitals, community, mental health and ambulance services - and although fewer staff are off sick there are more away on holiday".
A "high" air pollution alert has been issued for London.
A parliamentary environment committee has warned heat-related deaths could treble and rise to 7000 a year by 2050 unless the government plans ahead with strategies to protect people, especially the elderly.
Scientists have warned that climate change is making such heat extremes more likely, and the report comes as northern Europe swelters in a prolonged heatwave.
People in Berkshire have been told to stay out of the sun this week as a heatwave hits the country.