The government will publish health advice today on how to cope in a heatwave, to avoid a repetition of last year when during rising temperatures an extra 2,0000 people died in 10 days in England alone.

Throughout Europe about 35,000 people died, including 15,000 in France, from the extreme heat, prompting the chief medical officer, Sir Liam Donaldson, to draw up an emergency plan for the NHS, social services and other public bodies.

A temperature monitoring system set up with the Met Office will trigger four levels of alert.

It is thought that temperatures above 32C (89F) by day and 18C (64F) at night in London, over two successive days, could have a significant effect.

In other regions of England the strongest measures kick in at slightly lower temperatures: in the north-east 28C and 15C.

People over the age of 75, especially those living alone, and babies and young children, are among those most at risk of dehydration, heat exhaustion or heat stroke.

Leaflets at GP surgeries, walk-in centres, care homes and other organisations will advise people to stay indoors during the hottest hours, between 11am and 3pm, or keep in the shade, and to wear loose clothing and hats and drink plenty of water.

People are also advised to take cool showers or baths, to splash their face and necks several times a day, and to eat salads and fruit.

Care homes are advised to shade south-facing windows, ensure fridges are working, and be sure to have appropriate back-up staff in a crisis.

Sir Liam said: "Timely preventive advice can reduce excess deaths. In contrast to deaths associated with cold snaps in winter, the risk in mortality follows very sharply, within one or two days of the temperature rising. That means by the time a heatwave starts, the window of opportunity is very short indeed."

James Goodwin, head of research for Help the Aged, said: "As with extreme winter weather, acting as good neighbours can play a part in reducing the effect of hot weather on older people."