Gales and colossal seas have left only a third of the fleet still taking part in one of yachting’s toughest races as forecasters predict torrential rain for much of Britain.

While homeowners braced themselves for more severe weather, the field in the biennial Fastnet race was severely depleted after 44 mph winds and steep seas took their toll.

Just as it seemed as though summer had finally turned up, a wet and windy depression was sweeping Britain and threatening to trigger an early pattern of autumnal weather. Temperatures are forecast to drop below average for the rest of the month, and it seems unlikely that there will be anything for the rest of the summer to compare with the highest temperature of the year so far of 30C (86F), recorded on August 5.

Yesterday Bournemouth had half a month’s rain in a few hours, and was battered by 40mph winds. The Environment Agency has raised the prospect of flood warnings in coastal areas and on rivers. Some places are expected to have more than two inches of rain today. Nigel Bolton, at the Met Office, said: “There could be flash flooding. Inland, gusts of wind of up to 40mph are expected, and winds of up to 45mph around southern coasts.” Flood watches were in force at Christchurch Harbour in the South and Bridlington on the North Sea coast.

Off the south coast, by 10pm last night only 94 of the 271 yachts that started the race were still at sea, the weather having forced 177 to retire. This morning winds were expected to shift to the northwest and settle at around Force 6-7 (22–33 knots).

Ken Read, skipper of the American-registered Rambler, the first yacht to round the Fastnet Rock, spoke last night of “very squally, rainy and windy conditions for us between Start Point and Land’s End . . . We can report virtually no breakage even after some 40 knot squalls”.

When the Rambler rounded the rock shortly after 6pm it held a three-second lead over ICAP Leopard.

For many teams taking part in the 608-mile race from the Isle of Wight to the Fastnet Rock off southern Ireland and back to Plymouth the ferocious weather was too much. Although there have been no severe injuries, the memory of the 1979 race, when 15 people died and dozens of boats were lost in stormy weather, is in competitors’ minds. Yesterday the race organisers said that boats had been streaming into ports in Devon and Cornwall after their crews decided to retire and head for shelter. A race spokesman said: “For some boats it was not so much the wind, but the accompanying sea state that was proving exhausting.”

Notable retirements include the record-breaking yachtswoman Dee Caffari, who suffered damage to her main sail. The race leaders are due into Plymouth tomorrow.