Giles gives summer forecast

And now the weather forecast for the summer. The Jubilee bank holiday in the South will be splendid. Derby Day will be a delight. Wimbledon will be plagued with heavy showers. And the Commonwealth Games will be wet and cold but getting warmer.

Probably. That, says Bill Giles, former chief forecaster of the BBC Weather Centre, is how the next three months of British weather should look.

While the Met Office's first ever "seasonal forecast", issued this week, limits itself to the vaguest predictions about whether the summer in the whole of Britain will be wetter or drier, warmer or cooler than average, Mr Giles - who left the BBC in 2000 - is prepared to stick out his neck.

Last year, he set up the Weather Index (www.wpindex.com), a company he claims can forecast the temperature, windspeed, hours of sunshine and rainfall anywhere in Britain. This, he says, has had an accuracy rate of 80 per cent for medium range forecasting - up to 10 days - and 65 per cent even for forecasts up to three months ahead.

"That is twice as good as a guess - which is the yardstick against which one must measure it," he says.

Mr Giles uses records going back to the mid-17th century and national weather modelling from supercomputers around the world as well as the latest research on global warming.

Can he, though, beat the Met Office's "there is between a 60 and 80 per cent chance that summer will be warmer and wetter than average everywhere in Britain" prediction?

After 40 years as a forecaster, he is more aware than most of the maxim "fools rush in where angels fear to tread". No fool he. But in he rushed.

In Wales, East Anglia, and the South and South-West of England, the Whitsun bank holiday on 3 June will, he says, be warm with a risk of the odd shower, but getting better for the special Jubilee bank holiday on 4 June. Those in Scotland and the North will need to carry umbrellas and possibly jumpers.

Derby Day on 8 June will be blessed with sunshine throughout. Wimbledon, which starts on 24 June, is likely to be unsettled with heavy showers. "The weather will be coming in from the West, and although the heaviest rain will be in the North and Scotland, there will be some wet," says Mr Giles.

"They should be preparing for playing in the evenings and running over. It's a pity they couldn't postpone it until the second and third week of July, when it will be getting really warm."

The British Grand Prix on 7 July should be a scorcher. However, for the Commonwealth Games in Manchester from 25 July to 4 August, the picture is trickier, he says. "The models are giving conflicting advice. I think it will be pretty unsettled with rain and coldish temperatures, then becoming drier and warmer towards the end."

England's second test match against India at Trent Bridge, starting on 8 August, is also hard to call, he says, because if the wind is just slightly off his prediction of westerly, it could start off surprisingly well. However, he says: "It is not looking good at all. Cold and wet, although perhaps getting a bit better. Still not pleasant, though.

"Much better to go for Headingly (22-26 August) on the last couple of days," he says. "And I'd think better still if India bat first. The ball will be moving about a lot to start with."

Probably. "Weather forecasting is a matter of constant refinement," he says. "When we get to 10 days ahead, there may have been big changes. But if you've got to make a decision now, this is the best information available."

London's weather NOW