Summer heat: June temperature record in sight but it's not just about daytime maximums

Potential for record daytime temperatures on 30 June, and some unusually warm nights

My previous article focused on the statistic that the June 1976 UK temperature record of 35.6C at Mayflower Park, Southampton, is yet to be exceeded, despite the increase in summer heatwaves in recent years. In 2015 it was just one day away from being beaten, as temperatures rose above 36C at some sites on 1 July 2015. The record survived intact through the heat of 20/21 June 2025, when the highest temperature recorded anywhere in the UK was 33.2C.

But we have another shot at breaking that record on 30 June this year, on the last day of the month. It is not a certainty, and looks very "touch and go", with forecast models tending to go for a high somewhere between 34 and 36C on 30 June, most likely in inland parts of East Anglia and south-east England, although temperatures of 34-35C are also possible in some inland parts of Lincolnshire and even Yorkshire. Generally it seems that this area of eastern England has especially become more prone to very high temperatures in recent years. During the record breaking heatwave on 19 July 2022, 40C was reacted at some sites from Lincolnshire down to London, and highs of 38-39C were recorded in parts of Yorkshire.

With increasing summer heat, however, often the bigger contributor to mortality and to difficulty cooling down and sleeping at night is the night time temperatures, rather than the more headline-grabbing maximum temperatures. Last night, a large area of England failed to drop below 18C, and locally in Yorkshire and Lincolnshire it didn't fall below 20C. This is particularly unusual considering how far north the high night time temperatures penetrated - historically minima of 20C and above have been most common in southern England. A warm, humid tropical maritime air mass originating near the Azores was substantially responsible for this, as well as some unusually high sea surface temperatures around that source region.

This unusually warm night has happened before the daytime heat has really got underway. Today, the heat looks set to be more widespread in the eastern half of England, with 30-31C more widely and potential for highs of 32C, but as noted earlier it is especially on Monday 30 June when record breaking daytime temperatures are possible. Also on Tuesday 1 July, although the heat will be less widespread, temperatures of up to 35C are possible in East Anglia and south-east England.

We could also see minimum overnight temperatures of around 20C on Sunday/Monday and again on Monday/Tuesday, particularly around London.

An enhanced northwest-southeast split in summer

I have seen comments on the Netweather community and social media asking about whether there has been an enhanced northwest-southeast split developing in summer. Comparing the 1961-1990 and 1991-2020 long-term averages, this does indeed appear to have been the case. The mean maximum temperatures have increased more sharply in eastern and southern England than in western and northern Scotland, and in addition, summer sunshine has generally increased in eastern England, and declined in western Scotland. These trends are resulting in the east and south-east of England becoming hotter and sunnier relative to north-western Britain.

This enhanced northwest-southeast split will again be evident during the coming days. Much of north-west Scotland looks set to stay below 20C throughout the next few days, with the west and south-west of Scotland perhaps getting to around 22C on Monday. It will be hotter in the east of Scotland, but still with temperatures only reaching around 26-27C. Much of Wales and south-west England is also forecast to stay below 30C throughout the spell. However, it is anticipated that on Monday, most of England will reach or exceed 30C, with potential for places such as Manchester and Newcastle to reach 30 or 31C.