London and huge swathes of Britain are set to swelter in the second heatwave of the summer this weekend as temperatures soar to over 30C. More than 150 areas are forecast to see temperatures high enough to qualify as heatwave conditions, as defined by the Met Office.
You can see if your local area is about to see a heatwave by using our interactive map. Forecasters say it is possible that the UK could see the hottest June day on record over the next few days.
Temperatures are expected to climb over 25C in many areas of the country at some point in the next few days, with the hottest conditions expected on Monday. However, in much of Norfolk and parts of Essex there will be heatwave conditions for the next five days.
An official heatwave is declared by the Met Office when temperatures exceed a specific threshold for three consecutive days. However, the threshold varies in different areas of the country.
In London and parts of the South East, the temperature has to go over 28C for three days in a row for those areas to be in heatwave conditions. For the rest of the South East the threshold is lower, at 27C.
And in the South West of England, most of Wales, Northern England, Northern Ireland and Wales, it is counted as a heatwave if the temperature goes over 25C for three consecutive days. The Met Office definitions of heatwave threshold can be seen here.
Based on forecast conditions published by OpenWeather for the next five days, there are 156 local areas around London and the rest of the UK which are now expected to experience heatwave conditions. You can see if your area is forecast to experience heatwave conditions by typing your postcode into this interactive map:
The June UK temperature record stands at 35.6C, recorded both at Southampton Mayflower Park on June 28 1976 and at Camden Square, north London, on June 29 1957.
Met Office spokesman Graham Madge said: “There is a chance that we could meet or exceed that threshold set in 1976 and 1957. It is around a 20 per cent chance we could see weather observing stations exceed that – it is possible, not probable.”
A second amber heat health alert in two weeks has been issued today. The alert, which covers London, the East Midlands, South East, South West and East of England, started at midday on Friday and will last until 6pm on Tuesday.
Here is a full list of areas which are forecast to see temperatures which would count as an official heatwave, under the Met Office definitions. Areas which are not listed may still see very hot temperatures in the next five days but are not currently forecast to exceed the local heatwave threshold for three days in a row.
These areas are expected to exceed the heatwave threshold for all five of the next five days (from Friday 27 June to Tuesday 1 July)
Peterborough
Braintree
Chelmsford
Epping Forest
Harlow
Uttlesford
Breckland
Broadland
King’s Lynn and West Norfolk
Norwich
Tamworth
West Suffolk
These areas will see heatwave conditions on four out of the five days
London (28 boroughs)
Derby
Leicester
Rutland
Nottingham
Thurrock
Bedford
North Northamptonshire
West Northamptonshire
Cambridge
East Cambridgeshire
Fenland
Huntingdonshire
South Cambridgeshire
Brentwood
Colchester
Ashford
Canterbury
Dartford
Gravesham
Maidstone
Sevenoaks
Swale
Tonbridge and Malling
Tunbridge Wells
Charnwood
Harborough
Melton
Oadby and Wigston
Lincoln
North Kesteven
South Holland
South Kesteven
West Lindsey
South Norfolk
Gedling
Newark and Sherwood
Rushcliffe
Babergh
Mid Suffolk
Rugby
Warwick
Crawley
Mid Sussex
Coventry
Solihull
These areas will see heatwave conditions on three consecutive days
York
Luton
Bracknell Forest
West Berkshire
Reading
Slough
Windsor and Maidenhead
Wokingham
Milton Keynes
Southampton
Central Bedfordshire
Dorset
Buckinghamshire
Bolsover
Erewash
South Derbyshire
Mid Devon
Wealden
Cheltenham
Gloucester
Tewkesbury
Basingstoke and Deane
East Hampshire
Hart
Rushmoor
Test Valley
Winchester
Broxbourne
Dacorum
Hertsmere
North Hertfordshire
Three Rivers
Watford
Blaby
Boston
East Lindsey
Broxtowe
Cherwell
Oxford
South Oxfordshire
Vale of White Horse
West Oxfordshire
Lichfield
Ipswich
Elmbridge
Epsom and Ewell
Guildford
Mole Valley
Reigate and Banstead
Runnymede
Spelthorne
Surrey Heath
Tandridge
Waverley
Woking
Nuneaton and Bedworth
Stratford-on-Avon
Horsham
Redditch
Worcester
Wychavon
St Albans
Welwyn Hatfield
East Hertfordshire
Stevenage
Harrow
Hillingdon
Kingston upon Thames
Richmond upon Thames
Sutton
Monmouthshire
Why heatwaves in UK feel so much hotter than 30C heat abroad
Annie Shuttleworth, a meteorologist from the Met Office, told Stylist : “It is perhaps how heatwaves in the UK are perceived that makes them less manageable. When we experience heat abroad, we’re usually on holiday, and may be close to a pool or the beach. In general, buildings and infrastructure are also more set up for heat abroad – for example, there is more air conditioning.”
And it’s not just a figment of your imagination; humidity also plays a part in why 30C feels hotter in the UK than abroad.
A Met Office spokesperson explained to MyLondon in 2021 why the UK’s humidity can make heatwaves particularly challenging. “The level of humidity can be higher in the UK than in continental Europe. If humidity is high, it is harder for the human body to keep cool as your sweat doesn’t evaporate as quickly.”
They also highlighted the increasing occurrence of ‘tropical nights’ – a phenomenon where temperatures stay above 20C throughout the night, offering no relief from the heat and preventing our bodies from recovering.
Our body’s ability to lose heat depends on the temperature difference between our skin and the surrounding air, but this process is less efficient when external temperatures rise.
Sweat plays a crucial role in cooling us down through evaporation, yet high humidity levels can hinder this natural cooling mechanism.
“Sweating cools you down because when the water evaporates it transfers energy away from your body. However, sweating is less effective if there is already a lot of moisture in the air,” said Dr Matthew Patterson, a meteorologist, while speaking with BBC Science Focus.
This explains why the humid heat in the UK can feel more oppressive than the heat experienced in many other European countries and why health and weather warnings may be issued in the UK for temperatures in the low 30s, which might not be considered extreme elsewhere.
Climate expert Prof Hannah Cloke explained to BBC Science Focus how meteorologists and health organisations use various indicators to assess the impact that temperature, humidity, and wind speed have on our bodies.
“Forecasters and health agencies measure and forecast the effects of temperature, humidity and windspeed on the human body in terms of a ‘feels like’ temperature, or with indicators such as the Universal Thermal Climate Index (UTCI),” she said.
Prof Cloke highlighted why these measures are crucial for more than just statistical data: “Two regions might have identical temperatures, but one might feel OK, while the other leaves people dangerously overheated. Measures like the UTCI can provide planners with a much better understanding of where and when the impacts of a heatwave will be felt.”
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