Temperatures have been above 34C for six days in central London for the first time in almost 60 years.
The Met Office said that temperatures had reached 34.6C in central London marking the first time since at least 1961 that there had been six consecutive days of 34C and above.
This month's heatwave is due to continue over the coming days, with temperatures forecast to remain in the mid-30s in the south east of England on Wednesday.
A warming climate will lead to more heatwaves in the future, as well as hotter evenings, which could begin to impact people's health, the Met Office has warned.
Met Office spokeswoman Nicola Maxey said:
"Heatwaves are more likely, and so as well as more days we are going to see warmer nights.
Between 1961 and 1990 there were 44 nights where temperatures did not drop below 20C, although these were mostly associated with the heatwaves in 1976 and 1983, Ms Maxey said.
The heatwave has prompted police to warn holidaymakers that Devon and Cornwall are full after dealing with the highest number of incidents ever.
Devon and Cornwall Police has issued a desperate call for communities and tourists to respect the region after a weekend which saw record 999 calls.
There was also a huge spike in the level of anti-social behaviour and public order incidents as visitors flock to the south-west for a staycation.
