Temperatures could be in the 30s
People need to make sure they have a fair weather friend they can call on for aid in the event of a heatwave this summer, officials have advised.
The Department of Health's Heatwave Plan urges everyone to be aware of the health risks faced by elderly friends and relatives during a hot spell.
It says homeowners can stay cool by painting their houses white and planting shrubs for shade.
Forecasters say it is still too early to say if this summer will be hot.
Other tips include identifying the coolest room in the house.
For the very young and older people or those with serious illnesses, heat can be dangerous. In particular, it can make heart and respiratory problems worse.
TIPS TO STAY COOL
Shade south and west-facing windows
Paint buildings and surrounding walls white to reflect heat
Plant small trees and shrubs around buildings
Replace metal blinds with curtains with white linings to reflect heat outwards where possible.
In extreme cases, excess heat can lead to heat stroke, which can be fatal.
The Met Office says it is too early to tell whether it will be a very hot summer this year, but the signs so far are that it will be warmer than our last two summers and conditions could well trigger its heatwave warning system.
In London, this would mean daytime temperatures had exceeded 32C and night-time temperatures were over 18C degrees. In the North West, it would be 30C and 15C, respectively.
Wayne Elliott, Head of Health Forecasting at the Met Office, said: "Summer is nearly with us and it's a good time to prepare for the high temperatures that we can experience in this country."
The Heatwave Plan has been updated to advise those suffering breathing problems that although ozone levels increase in hot weather, they drop in the evening.
People with respiratory problems should stay inside during the hottest part of the day and windows should be kept shaded and closed when the temperature is hotter outside than inside.
Yvonne Doyle, Regional Director of Public Health for the South East Coast said: "This year's plan encourages everyone to take practical action before a heatwave strikes.
"Keeping the home as cool as possible during hot weather and remembering the needs of friends, relatives and neighbours who could be at risk is essential."
People are advised to contact their local environmental health officer if they have concerns for themselves or a vulnerable friend, neighbour or relative.
Environmental health workers at local authorities can visit to inspect the condition of a home for hazards to health, including excess heat.