The unpredictable spring weather has been blamed for disrupting grocery spend in the four weeks to April 21, with sales at the UK’s leading supermarkets growing at their lowest rate for nearly 15 months, according to Nielsen retail data.

During the four-week period, sales rose by 1.2% year-on-year – the lowest rise since January 2017 (excluding seasonality-affected periods).

Nielsen’s UK head of retailer insight Mike Watkins said: “The unpredictable weather finally started to disrupt grocery spend, particularly compared to last year which saw a mini heatwave in mid-April which meant a significant short-term boost to sales.

“A significant change in the weather can give supermarket sales as big a boost as an important event such as Easter, which is what happened in the week ending April 21 this year. The three days of hot weather helped sales jump 11% year-on-year. However, this wasn’t enough to offset the previous three weeks of poor weather.”

In the week ending April 21, shoppers spent £11m on sun care products, nearly treble the amount in the same period last year, and £28m on ice cream (double last year). Mixers for alcoholic drinks also saw particularly strong growth, up 51% with cider sales up 46%.

In addition to the overall slowdown in the amount shoppers spent, the number of items purchased year-on-year fell by 1.1% – the poorest growth figure for more than seven months.

In the 12 weeks ending April 21, Asda reported the most improved year-on-year performance of the top four supermarkets, with sales up 2.3%.

Sainsbury’s saw sales grow by 0.2% year-on-year, while Tesco’s grew 2.1%. The Co-op Group also saw year-on-year sales growth (+0.4%) with discounters Aldi and Lidl experiencing growth of 10.3% and 9.3% respectively.