"Indications for this year suggest the odds for a particularly hot summer, similar to those experienced in 2003 and 2006 across the UK, are around 1 in 8," it said.

High summer temperatures in 2003 caused thousands of deaths and a number of power plant closures across Europe.

As air conditioning systems were required to work harder for longer, demand for power rose at a time when several power plants closed, especially in France, because they themselves could not keep cool enough to run safely.

GLOBAL WARMING?

Summers warmer than the 1971-2000 average are now common, with the last summer of temperatures below the long-term average in 1998.

"Moreover, the underlying chance of exceptionally warm summers, such as experienced in 2003 or 2006, has increased," the forecasts said.

In the 1971-2000 period summer temperatures in the UK averaged 14.1 degrees Celcius. But since the mid 1980s the average UK surface air temperature has warmed by about 1 degree, or about twice the global warming trend averaged over all land areas, the Meteorological Office said.

The outlook for rainfall this summer is uncertain.

"There are currently no indications of an increased risk of either a particularly dry or a particularly wet summer," the report says.