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

The warning, for Thursday to Sunday, comes as the forecaster predicted 35C in places – 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 UK Health Security Agency has already issued an amber alert covering southern and central England from noon on Tuesday until 6pm on Saturday, with experts advising people to look out for those who are older or with existing health conditions, as well as young children.