Weather forecasters believe all time temperature records could be broken this week - with the heatwave showing no signs of coming to an end.

Very hot conditions are expected to persist across the UK through the working week, with temperatures expected to reach the high-20s or low 30s Celsius across the country, with 35 or 36 °C possible in a few places as the temperatures peak on Thursday and Friday.

The current record high temperature in Wales is 35.2 °C, recorded at Hawarden Bridge, Flintshire on August 2, 1990.

Thunderstorms blowing in from the East were expected to bring some respite to parts of eastern and central Britain today, but were expected to fizzle out before reaching Wales.

"The heatwave of 2018 will reach a peak for the time being on Thursday and Friday with temperatures likely to break the UK July record, and possibly the all-time UK record," said Paul Gundersen, Chief Meteorologist.

"Whilst many places will remain dry and hot, the thunderstorms on Friday could lead to torrential downpours in places with a much as 30 mm of rainfall in an hour and 60 mm in 3 hours.

"Large hail and strong, gusty winds are also likely and combined could lead to difficult driving conditions as a result of spray and sudden flooding."

However even if the storms do make their way all the way across the UK, the fine weather is expected to return by early next week.

Welsh Water say upland reservoirs are being used to release extra water into rivers during the unusually dry conditions to increase river levels and protect wildlife, and the company is advising their customers to use water "efficiently" to help maintain water supplies and protect the environment.

Alex Deakin, Met office meteorologist, said the reason for the continued hot weather is an unusually northern 'jet stream', the core of strong winds some five to seven miles above the Earth’s surface that blow west to east and move weather around the globe, creating a blocking pattern of high pressure over the country.

"The jet stream is important because it picks up area of low pressure that bring cloud and rain and takes them along with it," he said.

"This summer it's mostly been stuck to the north of the UK.

"Because the jet stream's been to the north so have the low pressure systems and that's why Iceland is having one of it's wettest summers on record.

"Meanwhile we across the UK have been to the South of the jetstream, on the warm side of the jet and without low pressure to interfere, high pressure has been dominating the weather keeping things dry, sunny and hot."