Warmer weather in September could cost non-food retailers £80m per week, according to a new report from the British Retail Consortium based on Met Office data.
The report, called Weather to Shop, found that this summer temperatures have been 2°C higher than average.
Met Office analysts compared BRC retail sales data with weekly temperature data and found that there was a clear relationship between temperature and increases in retail sales.
The impact is strongest from mid-August to early October, where warmer weather delays the purchase of autumn ranges. Over that period, for each degree warmer it is than the previous year, growth in sales is reduced by 1.1%, equivalent to around £40m per week.
Consequently if the current trend continues into next month, non-food retailers will see sales slump £80m lower each week than they would have been otherwise.
The report suggests that sales lost to unseasonable weather are largely recovered in the long run once temperatures normalise; meaning that temperature fluctuations are not behind the downward trend in growth of non-food sales that has been identified since 2014.
However warmer weather can have a significant impact on individual retailers, the report said.