Temperatures could climb into the low 30s and the heat is forecast to remain at night making sleeping uncomfortable.
The news comes as much of England has experienced a weekend of cooler air, cloud and rain.
A yellow weather warning for thunderstorms is in place in the east of the country today (July 6).
What is a heatwave?
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.”
How long will the heatwave last in the UK?
It’s difficult to gauge how long the heatwave will last and there are uncertainties about just how high temperatures will rise.
It also 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.
Recommended reading:
“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.”
