UK set for warmest weather of year so far over bank holiday weekend

Temperatures are forecast to rise as high as 30C in parts of the UK as a potential heatwave develops across the long bank holiday weekend.

Heat health alerts have been issued by the UK Health Security Agency across much of the Midlands and south-east England. The alerts run from 09:00 Friday 22 May until 17:00 Wednesday 27 May.

The mercury is set to climb each day for the rest of the week before the warmest weather of the year so far arrives.

If readings reach 30C before Monday, it will be the earliest date this has happened in the UK for over 70 years.

A heatwave in the UK is defined by the Met Office as at least three consecutive days with daily maximum temperatures exceeding a county-specific threshold.

The heatwave threshold temperature varies across the UK. In Greater London it is 28C, whereas in Northern Ireland and Scotland it is 25C.

It is likely that a few places could meet the heatwave definition during Friday, Saturday and Sunday. Areas such as London and the south Midlands are most likely to see this.

With the unseasonable warmth expected to continue into Tuesday and beyond, more parts of England and Wales could experience a heatwave after the bank holiday weekend.

Even in places where a heatwave is not likely, it still looks warm over the long weekend, with temperatures for most between 20C and 26C.

As early as Friday afternoon, temperatures are expected to reach up to 28C in south-east England. This will be the warmest weather of the year so far, exceeding the 26.6C recorded at Kew Gardens in April.

However, there remains uncertainty about how long the warm spell will last. The most likely scenario is for heatwave conditions to hold on until at least the middle of next week, with a change to something cooler and more unsettled from Thursday onward.

The main reason for the warmer weather is a change in the wind direction. The jet stream will shift north this weekend, allowing warmer southerly winds to bring hot air from southern Europe and north Africa.

It will feel very different compared to last week, when cold winds were blowing from the north.

It is rare to see temperatures up to 30C in the UK during the month of May. The last time this happened was in 2012 in Scotland. For England, this potential heatwave could bring the first May 30C since 2005. If the UK reaches 30C before Monday, this will be the earliest 30C since 1952.