Five-day heatwave starts within hours as UK weather maps show regions to hit 34C

A five-day heatwave during which we could see temperatures reach highs of 34C will start in a few hours' time.

After a few days of cooler weather, the Met Office said conditions are warming up, with heatwave criteria expected to be reached across much of the UK by the end of the week. Temperatures are expected to climb into the low 30s quite widely, forecasters say.

The mercury is expected to start rising again from tomorrow, with above-30C temperatures possibly lasting until the beginning of next week. While most of the country will be hot, Northern Ireland and Scotland will be spared from the scorching heat, as the Met Office says they are likely to be cloudier at first.

READ MORE: 23 areas to 'exceed heatwave criteria' for almost a week as Brits set to sweat

According to the weather service, it will be breezy near some North Sea coasts. Meteorologists said on Thursday temperatures could reach 31C, while on Friday parts of England and Wales could experience 32C or 33C.

The weekend is also set to be hot, with highs of 34C on the cards on Saturday, according to GFS weather model maps. Met Office Chief Meteorologist, Jason Kelly, said: "High pressure from the Atlantic will lead to a build in temperatures over the coming days, with heatwave criteria reached by the weekend.

"Whilst temperatures are expected to build day on day, becoming widely hot, they are unlikely to surpass those recorded at the start of the month. This heatwave is expected to be longer lived and extend further north and west into a larger part of the UK than previously seen this summer.

"Temperatures are expected to peak over the weekend and ease early next week. They are expected to exceed 30C in some areas from tomorrow, with peak temperatures of 31C on Thursday, with up to 32C possible in parts of England and Wales on Friday."

He added: "Scotland is also expected to meet heatwave criteria over the weekend. This hot spell is forecast to last longer and cover a broader area than previous ones so far this summer and pollen and UV levels will be very high in some areas. For updates, do keep an eye on the Met Office forecast as the picture develops."

In the UK, a heatwave is officially defined when a location records at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold. The threshold varies by county, from 25C to 28C.

The UK Health Security Agency (UKHSA) has issued yellow Heat Health Alerts covering parts of central and southern England, which are in force from today until 10am on Tuesday. The alerts cover London, the East Midlands, West Midlands, East Anglia, the South East and South West.

The UK saw its hottest day of the year so far when 34.7C was recorded at St James's Park in central London on July 1, while the capital also experienced the hottest start to Wimbledon on record. Provisional Met Office figures also showed England had its warmest June on record last month.

June's first heatwave occurred during the third week of the month, with heatwave criteria being met in many areas across England and Wales. The temperatures then broke with thunderstorms and showers across large parts of the UK, before high temperatures returned to close out the month.