Parts of England will see temperatures climb to highs of 30°C by day, but a key factor will be the night time temperatures. Lows in some areas may not fall below 18C.

Head of Health Forecasting at the Met Office, Wayne Elliott said: “We have been working closely with the Department for Health to develop this service, which is aimed at those vulnerable to high temperatures, especially the elderly. The last time a heat-health warning was issued was in the hot summer of 2006.”

The Heat-Health Watch is currently at level two with the probability of heatwave conditions at 70 per cent. The Met Office expects this to increase to level three during the course of the week.

Heatwaves can be dangerous, especially for the elderly, those with chronic diseases and the very young. Advice on how to reduce the risk can be obtained from NHS Direct or local pharmacists.

It will be predominately dry and sunny this week, but the build up of heat and humidity will set off some thunderstorms in parts of the UK.

Chief Forecaster at the Met Office, Martin Young added: “Temperatures are likely to build through the first part of this week, with a 60% chance of reaching 33C (91F) by mid-week, before becoming less hot by the weekend.”

Even though England will see the highest temperatures, all of the UK will have some very warm weather, with the continuing chance of thunderstorms in a few places leading to high rainfall totals locally.