The UK Health Security Agency has upgraded from yellow warning for eight parts of England
Heat health alerts have been upgraded from yellow to amber across most of England.
The UK Health Security Agency has warned the NHS will likely experience “significant impacts” across its services as a result of high temperatures which could reach 33C in some areas.
Experts added people could be affected by overheating in their workplaces and travel delays are likely.
The warning covers most of England, apart from the North East, from midday on Tuesday until 9pm on Sunday. The North East has a yellow warning in place.