Motorists without air conditioning told to 'postpone non-essential journeys' in extreme heat

It states that population-wide adverse health effects are expected, not just those who are the most vulnerable to hot weather.

Temperatures in some areas could reach as high as 39C, with the Met Office warning that delays could be seen on roads, in addition to road closures.

It adds: "Give yourself the best chance of avoiding delays by checking road conditions if driving, or bus and train timetables, amending your travel plans if necessary."

This has been echoed by the RAC, which explained that red extreme heat warnings are incredibly rare, and called on Britons to take them seriously.

Data from the organisation states that breakdown volumes are expected to be around 20 per cent higher today than what's normal for a Monday in late June.

Rod Dennis, road safety spokesperson at the RAC, said this week could break records for June with the number of vehicle breakdowns.

He continued, saying: "Drivers whose vehicles don't have effective air conditioning should strongly consider postponing any non-essential car journeys until the Met Office's weather warnings are lifted and temperatures drop.

"If this isn't possible, our best advice is to travel during cooler times of day. This is especially important for anyone travelling with vulnerable people, including young children and older adults, who are at greater risk from the intense heat.

"We'd also remind motorists never to leave pets inside a hot vehicle, as doing so can quickly become fatal."

The RAC's busiest June was three years ago, although it suggests that this week could "eclipse" those figures.

Mr Dennis urged drivers to remain patient with breakdown providers if their car has issues, as they will prioritise the most important roadside jobs.

"At these kinds of temperatures, road surfaces will soften, with darker patches of tarmac often the clearest indicator," he said.

Drivers across the country could see councils deploying gritting vehicles, which tend to be seen more often in the winter.

The RAC explained that applying a fine layer of granite dust can help vehicles maintain traction when roads are melting.

It also reassured drivers that if they see water underneath their vehicles, this will likely just be condensation from the air conditioning system.

Mr Dennis said: "There are simple steps motorists can take to reduce the risk of a breakdown in the first place, however.

"It begins with a few basic checks under the bonnet before setting out. Make sure oil levels are sufficient and top up if needed. Coolant should also sit between the 'min' and 'max' markers.

"If it isn't, top it up yourself when the engine is cold and have it inspected by an RAC mobile mechanic or reputable garage as soon as possible."