Fresher conditions are expected this week, with rain and even thunderstorms possible in some parts of the UK, after weeks of hot and dry weather.

A Met Office meteorologist said that the south of the UK will experience “changeable” conditions with temperatures turning “cooler”.

Despite the forecast, a yellow heat health alert has been extended until 9am on Tuesday for the South East, South West, and London.

The UK recently experienced its fifth heatwave of the summer with the hottest day of the year recorded in Kew Gardens, London, on Thursday when temperatures reached 38.1C.

In a Sunday update, Met Office meteorologist Tom Morgan said: “I can’t promise rain for all of us through the week ahead, but in the south at least, it’s looking like the most changeable week we’ve seen here – well at least since the end of June.”

A jet stream which has been far in the north of the UK has allowed high pressure to dominate, causing the recent excessively hot conditions, Mr Morgan said.

Mr Morgan said it would travel south, meaning that low pressure will dominate, adding: “So a much more changeable and at times unsettled outlook through the middle part of the week – low pressure will dominate and slowly drift its way southwards.”

He said it would start to turn “cooler” as wind switches to a northerly direction, adding: “So as well as some rain, showers, and even thunderstorms in places, it will certainly feel considerably fresher than recent weeks in the south.”

Showers are expected to become more widespread on Thursday with a mix of sunshine and rain earlier in the week, according to the Met Office.

Wildfires have ravaged parts of the UK, including in the West Midlands, where a blaze in Stourbridge destroyed 19 homes.

West Midlands Fire Service said they had been able to “significantly lift” cordons as households who were evacuated started returning to their homes over the weekend.

South Wales Fire and Rescue Service responded to “significant wildfire activity” on Sunday, with crews attending 14 wildfire incidents.

About 200 military personnel and crews from London, Greater Manchester, Cumbria and Bedfordshire have also been deployed to the region to assist.

On Friday, millions of people in England and Wales received an alert on their mobile devices warning them of a “very high risk of wildfires nationally”.

Several fire services have since uploaded statements asking people to only call 999 to report a genuine emergency.

South Wales Fire and Rescue Service said just before 7pm on Saturday that it was experiencing an “unprecedented demand”, having received 736 calls compared with an average of about 300.

The alert came after Prime Minister Andy Burnham described Britain as a “tinderbox” and a temporary ban on disposable barbecues was put in place.

A 50-year-old man has been charged with arson after several small fires were set in Hackney, east London.

Police and the London Fire Brigade were called to multiple reports of a man starting fires in London Fields, near Lansdowne Drive, Hackney, just after 5am on Saturday.

Later on Saturday, Isaac Shozi, of Bodney Road, Hackney, was charged with arson and remanded in custody to appear at Barkingside Magistrates’ Court on Monday.

The yellow heat health alert warns of “minor impacts” on health and social care services such as increased use of services by vulnerable people.