Where’s the heat coming from?
The heat and humid air is being drawn in from the south-west - and originates from the south-west Atlantic, Spain and Portugal.
How hot will it be?
It’ll be the first heatwave of 2020 with searing heat from Tuesday onwards - the hottest week of the year so far.
Temperatures will be in excess of 30C Thursday and Friday, most likely in the south east but the heat and humid air will be felt nationwide - as far as the Northern Isles of Scotland.
It’ll feel uncomfortably hot in urban areas of southern Britain with stuffy restless nights.
Even with some rain in places earlier in the week, it’ll feel warm and muggy.
How long will it last?
Into the weekend. After temperatures peak, expect thunderstorms to develop and it’ll feel a little more comfortable into Saturday - it will take time for temperatures to slide.
How unusual is it to have this heat so early in the summer?
June has the longest days of the year for maximum amounts of sunshine - last year saw temperatures reach 34C at the end of the month.
In 2017 we had our hottest June days for 40 years. The record stands at 35.6C in late June 1976.