UK Breakdown Callouts Jump 20% in Heatwave as Motorists Face Hours-Long Jams

Breakdown callouts across the UK jumped by a fifth last month as temperatures pushed past 30°C, and motoring experts are warning drivers to pack an emergency kit before every journey this summer. The warning follows reports of motorists stranded on the M25 for up to nine hours after a lorry crash, with many left without water, sun protection or phone chargers in baking heat.

Start Rescue, a leading breakdown provider and seven-time Which? Recommended Provider, says a few simple preparations can prevent a routine traffic jam from becoming a medical emergency.

A Fifth More Breakdowns Than Normal

RAC roadside patrols handled 20% more breakdowns than normal when the mercury topped 30°C across late June and into July, with the surge concentrated across London, Essex, Kent and Sussex. The AA recorded a 54% spike in overheating callouts in a single week.

The most common faults follow a predictable pattern. Tyre blowouts top the list: hot tarmac forces rubber to expand, and an under-inflated tyre on a motorway in July deteriorates far faster than the same tyre on a cold January morning. A 2026 industry survey found 38% of technicians named tyre blowouts as the single most preventable summer breakdown.

Engine overheating runs a close second, with 36% of technicians flagging it as a top warm-weather failure. Low or ageing coolant can cause catastrophic engine damage in sustained heat, with repair bills regularly exceeding £1,500. Battery failures round out the top three: high temperatures accelerate the chemical reactions inside a car battery, shortening its lifespan and increasing the chance of a no-start on the hottest days.

What to Pack Before Every Journey

Lee Puffett, Managing Director of Start Rescue, says preparation takes minutes but can prevent hours of misery.

“Even on a short trip, drivers can be caught in unexpected traffic jams that last for hours,” says Puffett. “That’s why it’s vital to keep these items in the car throughout the summer months.”

Start Rescue recommends carrying: plenty of water (at least one litre per person), suntan lotion, non-melting snacks, a first-aid kit and a mobile phone charger. Puffett also urges drivers carrying prescription medication to keep a dose in the car on every trip, not just long journeys.

“It only takes a few moments to pack these items and check the car over,” Puffett adds. “You might not be able to dodge traffic jams, but you can avoid breakdowns and the misery of being stuck in queues.”

Five Checks Before You Drive

A breakdown in 35°C heat is more than an inconvenience. Waiting for recovery on a hard shoulder in direct sun poses genuine health risks, from dehydration to heatstroke. A few checks before setting off dramatically cut the odds of a roadside stop.

First, check tyre pressures when the rubber is cold, before the car has moved. The correct figures are printed on a sticker inside the driver’s door jamb or in the owner’s manual. The legal minimum tread depth is 1.6mm, but the RAC recommends replacing tyres at 3mm for better wet-weather grip and reduced blowout risk.

Second, top up engine coolant to the max line on the expansion tank, but only when the engine is cold. Opening a pressurised coolant cap on a hot engine can cause severe scalding. If the coolant is brown or has visible debris, have it flushed and replaced by a garage.

Third, check oil levels using the dipstick. Oil thins in extreme heat, and running low accelerates engine wear. Fourth, fill up the windscreen washer reservoir. Insects and road grime build up faster in summer, and an empty washer bottle is an MOT failure.

Fifth, test the air conditioning before a long trip. A system that blows warm air likely needs a regas, which costs between £50 and £80 at most garages. Running without AC forces drivers to open windows, which increases fuel consumption at motorway speeds and does little to cool the cabin in stationary traffic.

What to Do If You Break Down in the Heat

If the temperature gauge climbs into the red while driving, switch off the air conditioning and turn the heater to maximum. This sounds counterintuitive, but the heater core acts as a secondary radiator, pulling heat away from the engine. Pull over at the first safe opportunity and let the engine cool for at least 30 minutes before checking fluid levels.

On a motorway, move to the hard shoulder or emergency refuge area, switch on hazard lights and get all passengers out of the vehicle and behind the barrier. National Highways advises standing well back from the carriageway while waiting for recovery. If you have no mobile signal, emergency phones on the motorway connect directly to the control room.

For drivers stuck in stationary traffic, keep the engine running if fuel allows, to maintain air conditioning. Crack a window if the engine is off. Drink water regularly, apply sunscreen, and check on children and elderly passengers, who are more vulnerable to heat exhaustion. The NHS warns that symptoms of heatstroke, including confusion, rapid breathing and loss of consciousness, require an immediate 999 call.