Put the porridge on hold. Leave the pullovers in the drawer. And if you're a pub landlord with a beer garden, throw it open. As October approaches, midsummer is returning.
Much of Britain is about to experience the best weather of the year, a sumptuous five-day interlude of cloudless skies and uninterrupted sunshine, with near-record temperatures for the season – and traders and businesses all over the country are preparing to cash in on a final open-air bonanza for 2011.
A large high-pressure system over the Continent is drawing a vast mass of hot dry air towards the British Isles from Southern Europe and even from North Africa, pushing temperatures up a full 10C above their seasonal norms.
From today, the hot weather will build up, and by Saturday, South-east England is likely to see highs of 28C (just under 83F) or possibly even exceeding that – threatening Britain's October record temperature of 29.4C, or 85F, which was set in Cambridge on 1 October 1985.
As the average seasonal high in the South-east is 18.4C (65F), this is very unusual and the warmest spell of autumn weather for 25 years is now in prospect. It is likely that roads will be crammed at the weekend as people flock to seaside resorts and crowd on to beaches for their last attempt at a tan.
Businesses which are weather-affected are rubbing their hands in anticipation. The Co-op is bringing in extra supplies of ice cream, while a spokesman for Morrisons said the supermarket had ordered the production of 200,000 more sausages and 120,000 more burgers, in the expectation that customers would be dusting off their barbecues over the weekend.
Pubs are putting more staff on the rota and planning to give their beer gardens and outdoor areas a stay of execution for what is expected to be one of the biggest weekends of the year.
"We think this could be bigger than almost any weekend in the summer gone by," said Andrea Solinas, general manager of the Avalon pub in Clapham, south London, which is reopening its 300-seat garden specially this week. "People will come because they know there won't be another weekend like it this year."
A spokesman for JD Wetherspoon, which manages 820 pubs across the country, said the company hoped its landlords would "throw the doors open" to outside seating areas in city centres.
Ice cream vans will be out on the streets for one last hurrah. Purbeck Ice Cream reported sales were up by 50 per cent against what was expected for September. The company's managing director, Hazel Hartle, said: "We love prolonging the summer a little, so everyone who has been working full-on can enjoy the weather at a slightly slower pace."
The warm spell will be hugely welcome after what has been the coldest summer since 1993, with August a chilly washout in many places. This week is likely to be the warmest since the school holidays began in late July.
But it's not quite correct to call it an Indian summer, said Paul Gundersen, deputy chief forecaster at the Met Office. "In terms of the classical definition, it would be expected to occur a little later in the season, more like October-November," he said. "But nonetheless, a very warm spell."
Wednesday Dry and sunny, some cloud in Ireland and north-west Scotland. Maximum temperature: 26C
Thursday Dry and sunny in England and Wales, rain in north-west Scotland and Ireland. Maximum temperature: 27C
Friday Dry and sunny in England and Wales, rain at times in parts of Scotland and Ireland. Maximum temperature: 27C
Saturday Dry and sunny in England and Wales, rainy in most of Scotland and Ireland. Maximum temperature: 27C
Sunday Dry and sunny in the south-east of England, rain and cloud moving in for the rest of the country from the north-west. Maximum temperature: 25C