The clothing stores in US cities are full of warm jackets, fur hats and boots, and ski caps, but no one is buying. Ski resorts are lying idle. Golf courses, normally closed for the winter, have reopened. Mosquitoes are still biting, geraniums continue to bloom, magnolia trees are flowering.

The times are truly out of joint in North America as exceptionally warm weather over most of the continent has sent records tumbling and has had an impact on the economic outlook for a range of sectors, including retailing, agriculture and winter sports.

Twenty cities from Pennsylvania to Maine set new temperature records on Thursday. In Boston and New York, the thermometer soared to 22 degrees, 15 degrees above average. In Portland, Maine, it reached 16 degrees, beating the previous record by three degrees. In Louisville, Kentucky, it touched 22 degrees, also three degrees above the record.

The extended warm spell, due to weather patterns that have kept air flowing up from the Gulf of Mexico and trapped colder air up north, is keeping consumers out of stores and shopping malls. Chain-store sales fell 1.7 per cent last week and an Instinet Redbook survey said retailers blamed the warm weather for lacklustre results.

Combined with growing unemployment, the major stores are now reporting the weakest November results since 1990. The holidays are crucial for retailers, as November and December sales account for a quarter of annual retail sales. The outlook for the Christmas season is grim, with the balmy weather expected to continue for several more days.

Apparel and department stores are suffering the most, with big discounts on piles of unsold scarves, coats and turtle-neck sweaters.

Burlington Coat Factory Warehouse, for example, said sales at its stores slumped 13.2 per cent in November due to the heat wave.

Even in normally frigid Canada, the warm weather is disrupting sales. The Sears Canada department chain is experiencing a "sales meltdown" because of warm weather, according to the Toronto Star, with sales falling 4.5 per cent in November.

"Clearly, the last decade had the warmest winters in history. Most years, winter is now coming after Christmas," said Mr Rick Harrison, head of merchandising at Mark's Work Wearhouse stores in Toronto.

Many other product sales are affected. After September 11th, sales of firewood doubled as people feared the price of oil and gas would soar. Instead, the average cost of heating a home this winter has tumbled from $400 to $300.

In New York hardware stores, snow-clearing equipment and heaters are languishing on the shelves.

While ski resorts remain closed - the season should have started more than a week ago - November has been a record month for golf courses. At Cleveland Metroparks course, golfers played 23,000 rounds in November, compared with 10,000 rounds for the same month last year. The course, usually snowbound in winter, plans to stay open until the New Year.

On one day last week the golf club at Walkersville, Maryland had 150 golfers rather than the usual 20. Two golf courses opened in the Minneapolis-St Paul metropolis area, often covered with snow from late October.

The extended Indian summer has been good for some business. In Manhattan, the Patagonia store sold more surfboards last month than during any other November. In Chicago, a Mitsubishi car dealer was reported as saying: "It's a beautiful thing, I have had three or four people a day who want to look at cars. Usually in December, it's only one a day."

The warm temperatures have fooled some plants into blooming and they will probably not flower in the spring. Owners of apple orchards in the north-east are particularly worried that the crop may fail next year.

However, global warming may not be all bad for agriculture. The economic benefits could outweigh the overall costs, according to Dr Robert Mendelsohn, author of a new book, Global Warming and the American Economy.

"The biggest beneficiaries will be farmers who will have longer growing seasons and crops that grow faster thanks to extra carbon in the air," he said in yesterday's New York Times.

"The losers are the poor tropical countries, not the rich industrial countries that have done the most polluting," Dr Mendelsohn added.