High temperatures could lead to an official heatwave, with much of the UK set to enjoy “very warm, locally hot weather” over the next few days, forecasters have said.

The Met Office said the mercury could reach up to 32C in London by Tuesday while long-term forecasts remain warm despite the chance of thunderstorms during the week.

The heatwave threshold is met when a location records at least three consecutive days with maximum temperatures exceeding a designated value, according to the Met Office.

This is 25C for most of the UK, but rises to 28C in London and its surrounding area, where temperatures are typically higher.

The warm surge is down to a wave of high pressure across the country and warm air rising from the south, creating dry, fine and sunny conditions and bringing temperatures up.

Simon Partridge, forecaster at Met Office, said: “There is certainly potential that it could become an actual official heatwave, because in the spells you’ve had before it hasn’t actually met all the criteria.

“If there’s not, it’s very close to it, and if you’re out and about and a member of the public then it’s going to feel like a heatwave anyway, because also overnight things are going to turn a little bit more humid and muggy day-on-day as well.”

Temperatures were expected to reach 27C in some local areas on Sunday, before highs of 29C on Monday and 32C on Tuesday, both in south-east England, are forecast.

The hottest day of the year so far saw a temperature of 31.9C recorded at St James’s Park in central London on July 19.

Many parts of the country will see temperatures four to five degrees warmer than average for this time in July, the forecaster said.

Only the far north-west areas of Scotland and parts of Northern Ireland will see some cloud and possibly rain on Monday and Tuesday.

However, this summery spell could end abruptly on Wednesday with some heavy thundery rain expected, although uncertainty remains whether this will be just across the south of England or other parts of the UK.

Despite the sudden showers, temperatures are expected to stay high heading into the first week of August.

Mr Partridge said: “Usually you get these thunderstorms come through and then everything’s a lot cooler and fresher, but although it will be a bit fresher at the end of the week, it will still be about where we should be, if not a degree or so warmer. So a bit of summer is on the cards.”