Unseasonably warm weather can cost retailers £40m per week for each degree that temperature is raised, according to analysis by the Met Office and the British Retail Consortium (BRC).

The effect is strongest from mid-August to early October when higher temperatures make consumers put off buying clothing for autumn and winter.

In that period, sales growth is reduced by 1.1pc for each degree above temperatures seen a year previously. This equates to £40m a week in lost non-food sales.

Nearly half of spending growth variation in those weeks can be attributed to weather differences, according to the research.

Climate is particularly important in men’s clothing, where it can account for more than 70pc of year to year differences in sales growth between mid-September and early October. Each degree that it is warmer than the year before can lower sales growth by 2.4pc.