As the Met Office forecasts a steep rise in temperatures over the next couple of days, RAC spokesperson Rod Dennis said:

“With the temperature ramping up very rapidly this week we’re expecting a short, sharp spike in breakdowns, especially in central and southern parts of the UK. It’s important drivers don’t get caught out, so we’re advising they check their cars’ oil and coolant levels as soon as they possibly can, particularly if they have a long trip planned in the hottest part of the day. Drivers should also stay hydrated which has been shown to have a positive effect on their concentration levels. Passengers should also be kept as cool and comfortable as possible so carry plenty of water and plan in sufficient breaks to avoid an already hot car becoming even more heated.”

The RAC website carries a guide to avoiding breakdowns during hot weather.

From Met Office:

Temperatures will continue to rise as we go through the rest of the week.

Many parts of the southern half of the UK are likely to exceed 30C and may even reach 34C in some places, by Friday.

Away from the northwest, where a series of fronts are bringing rain and cloudier weather to parts of Scotland and Northern Ireland, the weather is fine and dry. The settled conditions are allowing temperatures to build day-on-day with the hottest temperatures expected to be reached by Friday for many. 

Met Office Deputy Chief Meteorologist, Jason Kelly, said; “The heat is a result of a mix of home-grown warming due to a high pressure over the southern half of the UK, as well as a south westerly airflow bringing warm air, which has been over continent through the week, across the country.”

“This is the first spell of hot weather this year and it is unusual for temperatures to exceed these values in June. Some areas may see warm nights with minimum temperatures expected to be in the high teens or even low 20Cs overnight, especially in urban areas such as London.”