WHEN they walk past boarded-up windows, shoppers could be forgiven for blaming competition from out-of-town stores, supermarkets or the internet.
But they are unlikely to know that one of the biggest challenges facing traders is not the threat from rival retailers but a much more unpredictable concern: global warming.
The buying habits of shoppers are changing as milder winters and hotter summers transform patterns of demand.
Heavy coats are making way for thin-strapped dresses, heavy drinks such as Guinness are being exchanged for lighter tipples such as rose wine and increasingly exotic plants are in vogue at garden centres.
And the changes are becoming harder to predict. Last year, forecasters were certain of a bitterly cold winter. It never arrived, and retailers have entered 2007 with shelves cluttered with unwanted outdoor coats and heavy waterproof jackets. Likewise, the paradox of water shortages and year-round heavy rainfall has washed away the retail rule-book when it comes to selling everything from barbecues and bedsheets to sandals and swimshorts.
"It is impossible to underestimate the importance of weather for shops," said Fiona Moriarty, the director of the Scottish Retail Consortium. "Unpredictable weather was a major problem for retailers throughout 2006 and with energy bills now the biggest cost behind wages, climate change is a very big issue on the high street."
Her comments came as Blacks, the leisure chain which also trades under the Millets and O'Neill brands, announced it was closing 45 stores and cutting up to 100 jobs and cited Britain's increasingly erratic climate as one of the reasons behind a sharp dip in sales.
While there is no doubt that the chain has problems which extend beyond the weather, global warming has clearly influenced its success in recent months. Britain's dry summer, combined with the World Cup and the lack of a Glastonbury Festival, saw a slide in sales of tents, waterproofs and other camping equipment during the first half of 2006. It has now warned that profits for the second half of the year would come in "substantially below" market expectations after sales fell 6 per cent in the key five weeks to 30 December amid mild winter weather.
Ms Moriarty said: "The main problem is that it is so hard to predict where we will be in the future. This season the shops were full of winter coats, hats, gloves and scarves and now, after a mild winter, retailers are having to shift unsold stock at a reduced price.
"Cold conditions and a late Easter gave Scottish shops a slow start to spring and summer lines last year, too. July's very hot weather helped tourism and boosted food and drink sales but put some shoppers off venturing onto sweltering high streets so there are also long-term implications for predicting footfall - the number of shoppers who walk through the door."
Among the first to spot the effects of global warming were Britain's garden centres. James Barnes, the chief executive of Dobbies, said it was now selling olive trees outside southern England and that bedding plants were no longer a seasonal item.
"We can now sell plants such as tree ferns and hibiscus that we wouldn't have considered stocking ten years ago," he said. "The idea of the 'room outdoors' has been driving sales of patio furniture and barbecues for some time now and there is strong growth in outdoor furniture."
The world of fashion is also cutting its cloth according to the weather. A spokeswoman for retail analysts TNS Wordpanel said sales of shorts were due to reach ten million in 2007 compared to only seven million last year. She said: "The volume of sales of lighter items is definitely on the increase, as you'd expect with hotter weather."
Richard Gray, executive fashion editor of the style magazine 10, said: "Styles are changing toward lighter and less dense fabrics such as cotton, and summer wear is becoming increasingly important, at the expense of the winter coat."
But others are less convinced of the importance of climate change on sales. Anna Nugent, an analyst with Euromonitor, said that long-term rises in sales of cider and rose wine were more easily explained by changing tastes. "We all want to avoid drinking what our parents would have chosen because it is seen as unfashionable and that, more than anything, is what explains how some drinks come into favour.
"Light beer has been growing very slowly and that might be down to the fact that, with an ageing population, less strong drinks are more in demand. These things go in cycles. Ales and stouts are doing really well in the United States at the moment."
And Bill Brown, manager of an outdoor equipment store, Hilltreck, based in Aboyne, Aberdeenshire, said sales of coats and waterproofs had not suffered. "We're doing really well, particularly Ventile jackets which customers can't seem to get enough of. You still need protection from the rain."