Simon King
Lead Weather Presenter
The UK has seen its hottest day of the year so far on Friday as 30.9C was reached at Wisley in Surrey.
The previous highest temperature recorded so far this year was 30.5C also at Wisley on 26 June.
Temperatures across the UK are widely expected to reach 25 to 31 Celsius on Friday as the hot spell peaks.
Cooler weather will spread eastward over the weekend with temperatures more typical for July expected by Sunday.
Heat building
After a pretty cool start to July where temperatures have been around 2C below average, many of us have welcomed some summer-type warmth.
Many places haven’t reached 25C since the short burst of warm weather at the end of June.
Heat health alerts are in force across the Midlands, eastern and southern England until 11am on Saturday.
These alerts are primarily for the health and social care services, warning that heat could impact the elderly and those with underlying health conditions.
Temperatures must reach a certain level on three consecutive days to meet the Met Office definition of a heatwave
Is this a heatwave?
For this to be declared a heatwave the Midlands, much of southern England and East Anglia would need to have three successive days above 27C.
That temperature theshold rises to 28C for London and some of the home counties.
With temperatures starting to fall by the weekend, we are likely to fall just short of this brief hot spell officially being a heatwave in most areas.
With cooler air moving in from the west on Saturday, along with heavy and thundery showers, temperatures will drop for many.
Though across eastern areas of England the heat will remain for one more day with highs expected to reach 26C.
By Sunday the very warm and humid air will have cleared so temperatures across the UK will be more typical of mid-July at 16 to 22C.
Is it unusual to reach 30C in summer?
Temperatures have reached or exceeded the 30C mark every summer since 1993, so it’s not unusual for the weather to get this hot.
The number of days we see over 30C during summer has vastly increased in recent decades compared with the early 20th Century as a result of climate change.
