High street shops saw a like-for-like sales fall of 2.2% in April due to the bad weather, making it the fastest fall in a year.
Latest figures for May saw consumers take advantage of clearance sales to pick up bargain knitwear, with perfumes and cosmetics sales boosted by promotions and discounts.
The recent sunny weather has boosted sales of barbecue meats, salads and ice creams and swimwear.
David McCorquodale, head of retail at KPMG, which compiled the data, said: "While sales didn't soar through the roof, this is still a very creditable performance from UK retailers. Promoting the right product at the right price made the difference in May."
The British Retail Consortium director general Helen Dickinson said retailers had contended with changeable weather patterns with a good result as the outcome. She said:
The signs are that temporary discounts and offers worked well to tempt shoppers into stores and clear some of the stock that had been slow to sell during the preceding months.
This strategy paid off particularly well for furniture and flooring, May's best-performing category.
Customers are still price-conscious but responding well to good deals, especially for big-ticket items. But volatile economic conditions mean that this will remain a delicate balancing act for some time to come.