UK: Warming up this week

The start of the week will be fine and dry with sunny spells for many in England and Wales. However, a series of weak fronts will push into Scotland and Northern Ireland bringing cloudier weather here with a chance of some light rain, especially across the northwest.

From Wednesday onwards while cloud, rain and breezy conditions continue across the northwest, it will become increasingly warm in the south as high pressure builds. This will bring settled conditions allowing temperatures to build day-on-day and for it to become hot, or even very hot, across parts of England and Wales by Friday.

Met Office Deputy Chief Meteorologist, Dan Rudman, said; “Temperatures will continue to rise as we go through the week, becoming well above-average by Friday when many parts of the southern half of the UK are likely to exceed 30C and may even reach 34C in some places.”

“This is the first spell of hot weather this year and it is unusual for temperature to exceed these values in June. Many areas will also see some warm nights with minimum temperatures expected to be in the high teens or even low 20Cs for some overnight.”

“The heat is a result of a mix of home-grown warming in the day due to high pressure, as well as a southerly airflow introducing some of the warm air from the continent to UK shores.”

A Level 2 Heat-Health Alert has been issued for the much of southern and central England, with a Level 1 Alert in place for northern England.

Agostinho Sousa, Head of Extreme Events and Health Protection at the UK Health Security Agency, said: “Temperatures are forecast to reach 30C in some parts of the south on Friday and we want everyone to enjoy the hot weather safely when it arrives and be aware of good health advice for coping with warmer conditions.

“During periods of hot weather it is especially important to keep checking on those who are most vulnerable, such as older people and those with heart or lung conditions. Make sure to look out for signs of heat exhaustion and follow our simple health advice to beat the heat.”

Heatwave criteria

A UK heatwave threshold is met when a location records a period of at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold. The threshold varies by UK county.

Although some parts of England may perhaps meet these heat wave criteria it looks like this spell of warm weather will be relatively short-lived. Milder conditions look likely to return later in the weekend with temperatures trending back to around average for June as we see cooler air push across the country from the northwest.

The highest temperature reached in the UK so far this year is 27.5C at Heathrow on 17th May. It is still relatively unusual for temperature to reach the mid 30Cs in June and you have to go back to 1976 for the highest recorded June UK temperature (records date from 1884). 35.6C was reached at Southampton Mayflower Park on 28th June 1976. The average June maximum temperature for the UK as a whole is 18C.

An Environment Agency spokesperson said: “There is a low-risk of drought for public water supplies this summer. However, further hot, dry weather could put pressure on some areas.

“Dry weather this spring has led to receding river flows and reservoir levels across central and south western England in particular. Early June rainfall has offered some relief with river flows improving compared to the end of May, however a third of river flows remain below normal for the time of year.

“As always, we continue to work with water companies and wider stakeholders to closely monitor water resources and take action, where necessary. People should use water wisely and follow advice from their suppliers.”

A cold front from the north introduces more uncertainty on how long the highest temperatures will hang on for Saturday, with areas to the southeast currently most likely to hold on to warmth the longest, although the extent of this is still being determined.

Climate change

An increase in the frequency, duration, and intensity of extreme high-temperature events and heatwaves over recent decades is linked to the observed warming of the planet and can be attributed to human activity. Previous Met Office research has shown that the frequency of high-temperature extreme weather events outnumbers low-temperature extremes by about nine to one.