Temperatures are rising in Pembrokeshire and Ceredigion as west Wales braces itself for another heatwave, which could last longer than last month’s hot spell.

It comes as the Met Office issued a four-day amber warning for extreme temperatures in parts of England and Wales as a new heatwave looms.

The warning does not cover the Tivyside area – but temperatures in the county are expected to reach highs of 28C at the end of the week.

An amber warning, for Thursday to Sunday, comes as the forecaster predicted 35C in places or even an “isolated” 36C – below last month’s record temperatures, which peaked above 40C in some spots.

The vulnerable are likely to experience adverse health affects, while the wider population could also be affected, the alert said.

Delays to travel are possible and there is an increased risk of water accidents and fires as more people visit coasts and beauty spots, the Met Office also warned.

The Met Office said temperatures will likely rise into the low to mid-30s in the warning area.

Outside the warning area, heatwave thresholds – which are met at different temperatures in different parts of the country – are still likely to be met for much of the UK, with temperatures widely into the high 20s and a chance of a few spots seeing temperatures into the low 30s.

Tivyside Advertiser: Beachgoers enjoying the sun in Tenby. Pic: Gareth Davies PhotographyBeachgoers enjoying the sun in Tenby. Pic: Gareth Davies Photography

Met Office deputy chief meteorologist Dan Rudman said: “Thanks to persistent high pressure over the UK, temperatures will be rising day-on-day through this week and an extreme heat warning has been issued.

“Temperatures are expected to peak at 35C on Friday and Saturday, or even an isolated 36C on Saturday. Elsewhere will see temperatures widely into the high 20s and low 30s Celsius.

“Coupled with the high daytime temperatures there will be some warm nights, with temperatures expected not to drop below the low 20s Celsius for some areas in the south.”

With the latest heatwave coming after months of low rain, which have left the countryside and urban parks and gardens tinder-dry, households in some areas are being urged not to light fires or have barbecues.

The Met Office’s fire severity index (FSI), an assessment of how severe a fire could become if one were to start, is very high for most of England and Wales, and will reach “exceptional” for a swathe of England by the weekend.

Scientists warn that the likelihood of droughts occurring is becoming higher due to climate change, driven by greenhouse gas emissions from burning fossil fuels and other human activities.

Climate change is already making heatwaves more intense, frequent and likely, with last month’s record temperatures made at least 10 times more likely because of global warming, and “virtually impossible” without it, research shows.

Two water companies have announced hosepipe bans – including Pembrokeshire - with others warning they may have to follow suit – prompting political debate about whether restrictions should be brought in when utilities are leaking billions of litres of water a day.

Tivyside Advertiser: Visitors to Tenby enjoying the sun. Pic: Gareth Davies PhotographyVisitors to Tenby enjoying the sun. Pic: Gareth Davies Photography

Additional reporting by PA.