UK heatwaves - data and advice

UK heatwaves are becoming more frequent, bringing prolonged periods of higher temperatures – which can seriously impact drivers.

Hot weather can cause vehicles to overheat and result in dehydration for the person behind the wheel.

In this driving in the UK guide, we look at the definition and what drivers should do during a heatwave.

What is a heatwave?

According to the Met Office, a heatwave is an extended spell of unusually hot weather for a particular area and time of year, sometimes accompanied by high humidity.

In the UK, a heatwave is officially recorded when a location experiences at least three consecutive days with daily maximum temperatures at or above a defined threshold.

These thresholds vary by region, ranging from 25°C in parts of Scotland, Northern Ireland, northern England, Wales and south-west England, to between 26°C and 28°C in central and south-east England.

Record temperature in England

Both England’s and the UK’s record temperature happened in Coningsby in Lincolnshire on the 19th July 2022 of 40.3ºC.

Record temperature in Wales

On the 19th July 2022, record temperatures were set in Wales in Hawarden, Flintshire at 37.1ºC.

Record temperature in Scotland

Charterhall in Scotland set record temperatures in the country on the 18th July 2022 with 34.8ºC.

Record temperature in Northern Ireland

Northern Ireland’s highest ever recorded temperature was 31.3ºC, which was set on 21th July 2021 in Castlederg, Country Tyrone. 

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Advice for driving in a heatwave

Driving in a heatwave can be both uncomfortable and risky, so preparation is vital.

Higher temperatures can affect both the driver and the vehicle, increasing the likelihood of a breakdown.

• Check your vehicle before travelling: Make sure that your coolant and engine oil is topped up – as well as your windscreen washer fluid. To help you with this, we have guides on how to check your coolant and how to check your oil
• Keep your tyres in good condition: Heat increases tyre pressure, so inspect them regularly. Also look out for any cracks or damage to the tyres and check the tread depth.
• Avoid driving at peak heat if possible: Check the weather forecast before leaving and try not to travel when the day reaches its highest temperature. Early mornings or in the evening are better options.
• Use sun protection: Sunglasses and sun cream are essential for drivers during the summer months – so make sure they are packed in the car.
• Air conditioning: Before the hot weather arrives, check your vehicle’s air con is working correctly. If the air blows warm or hot, the air con may need re-gassing.
• Take regular breaks: Drink lots of water and use rest stops to refresh and refocus.

Never leave pets in the car in hot weather. According to the RSPCA, even when it's 22 degrees Celsius outside, the interior of the car could reach 47 degrees within 60 minutes.

How many heatwaves does the UK experience every year?

According to the Met Office, there are between 4 and 10 heatwaves each year in the UK.

When is the next heatwave?

High pressure is set to stay in control, bringing another spell of mainly dry, sunny and very warm weather across much of the UK, although temperatures are expected to ease slightly towards the weekend.

Monday will be very warm or hot across southern and western areas, with temperatures reaching around 31°C in southwest England and 28°C in Wales. In contrast, eastern and northeastern coastal areas will be cooler, with breezy conditions, more cloud and highs only in the upper teens. Heat Health Alerts issued by the UK Health Security Agency (UKHSA) remain in force.

Temperatures are likely to peak on Tuesday and Wednesday, reaching 30°C to 32°C in parts of England and Wales. Most areas will remain dry with plenty of sunshine, although some eastern coastal locations may stay noticeably cooler due to onshore winds and periods of cloud.

With much of the UK experiencing further hot weather, including a third heatwave of the year in some areas, RAC road safety spokesperson Rod Dennis said: “After two spells of exceptionally hot weather in recent weeks, the nation's vehicles will now be facing their third big test of reliability this summer. The very high temperatures are putting extra strain on cars, particularly older ones and those that already have underlying issues.

"We’re consistently seeing hundreds more breakdowns every day compared to what is normal for July, with overall daily call-outs up by 20%. We expect breakdown numbers to continue to rise again over the coming days, with battery failures, overheated engines and tyre-related problems all becoming more likely as temperatures keep climbing.

“No-one starts the day expecting their car to fail them, but breaking down in a heatwave can be far more than just an inconvenience. Being stranded in direct sunlight can become dangerous very quickly, especially for families travelling with children, older people, pets or anyone with a health condition. That’s why drivers should make sure they have plenty of water with them, and think carefully about what they would do if their journey doesn’t go to plan. Using our acronym 'SHADE' can help here - by remembering Suncream, Heat protection (ie a hat or umbrella), a breakdown assistance App, Drinks and Essential medication, drivers can be sure they’ve got the most important things with them if they break down.

“A few simple checks before setting off can make a big difference, as so many of the incidents our patrols are going out to are avoidable. Ensuring coolant and oil are at the correct levels, checking tyres are in good condition and properly inflated, and not ignoring dashboard warning lights are all sensible steps that can help reduce the chances of ending up stranded at the roadside. Drivers should contact an RAC Mobile Mechanic if anything doesn’t feel right, or if they know their vehicle hasn’t been serviced in the last 12 months.

“With hot weather now becoming a more regular feature of UK summers, preparing both themselves and their vehicle for extreme temperatures is more important than ever."

Hottest temperatures by month in the UK

According to the Met Office, these are the hottest temperatures ever recorded in the UK for each month of the year.

^{Source: Met Office}