The high street has recorded its worst year-on-year May performance for 12 years despite the royal wedding, warm weather and two bank holidays, figures show.
Sales were down 2.2% on May last year, making it eight months since in-store like-for-like sales have shown growth of 1% or more, according to BDO's High Street Sales Tracker.
The figures highlight the volatility on the high street that is contributing to some high-profile casualties and store closures from the likes of House Of Fraser and Marks and Spencer.
Stores were deserted for Saturday trading on May 19 as more than 13 million people in the UK tuned in to watch the royal wedding, and the exodus contributed to a 5.1% year-on-year drop in in-store sales of discretionary items for the third week of the month.
The lifestyle sector saw year-on-year sales drop by 3.8% in May, but homeware retailers were hit particularly hard with like-for-like sales falling 15.2%.
Sophie Michael, head of retail and wholesale at BDO, said the figures highlighted the volatility on the high street.
She said: "Consumer spending patterns continue to be both volatile and unpredictable, making it increasingly difficult for retailers to identify trends and respond accordingly.
"Whether it's falling discretionary income, unexpected weather or a growing preference to spend on experiences, the result is creating growing challenges on the high street which are clearly affecting retail performance."