How long will the third heatwave of the summer last and how hot will it get?

Temperatures are set to top 30C in some parts of the country this week, as the UK prepares for its third heatwave of the summer.

The Met Office has warned Britons could face more warm and uncomfortable nights ahead, with mercury set to creep up from Wednesday.

If the temperatures remain high until Friday, the UK will officially mark its third heatwave of the season.

Temperatures are expected to climb even higher over the weekend into the low 30s.

Marco Petagna, senior meteorologist at the Met Office, said: “I think Wednesday is probably going to be the day when we could start to reach the thresholds of 25 to 28 degrees, depending on where you are.

“But of course, you need three days at those temperatures for it to be able to be called a technical heatwave.

“So, although the temperature will be reaching the criteria, we probably won’t actually reach an official heatwave until around Friday, to give the three consecutive days at those temperatures.

“But temperatures are going to continue to climb as we go toward the end of the week and certainly by Friday and Saturday we could see 30 degrees, perhaps just nudging into the low 30s.

“At the weekend, we could just start to see humidity increasing a little bit as well and nighttime temperatures look like they are going to be, so it will be starting to become more uncomfortable by night.”

It is uncertain exactly how warm it will be for how long, though it appears as though the UK will avoid the stifling weather of the high 30s and low 40s seen in the Mediterranean.

Mr Petagna said: “It’s a bit of a question mark going through the weekend early next week as to how long the heat will last and how high the temperatures will get, because some models are sort of pushing the heat away a bit more quickly, whereas others keep the heat going.

“At this stage it looks as though certainly into next weekend, we should hold on to hot weather across the south of the UK and temperatures could again certainly get into the low 30s in a few spots.

“And we are going to see some very high pollen and very high UV levels as well.

“But at this stage, we’ve managed to escape some of the very highest temperatures, those seen across Spain and Portugal in particular, where it has reached the mid-40s.”

It follows a weekend of cooler air, cloud and rain in most of England, and a yellow warning for thunderstorms in the east of the country on Sunday.