A four-day "extreme heat" warning came into force in parts of England and Wales on Thursday.
This is as temperatures poised to exceed 35 degrees Celsius (95 degrees Fahrenheit) in another scorching heat wave that could pressure water supplies and transport services.
The Met Office said its amber warning, its second-most severe will last until the end of Sunday and cautioned that people vulnerable to extreme heat could face adverse health effects.
It added that temperatures are expected to peak at 35 degrees Celsius on Friday and may hit 36 degrees Celsius in some places on Saturday.
During July's heatwave, Britain, which is less used to such high temperatures, faced power outages, damage to airport runways and rail tracks and dozens of blazes in London, where the fire brigade faced its busiest week since World War II.
Other European nations have also faced a scorching heat wave in recent weeks with temperatures often exceeding 40 degrees Celsius.