Sunshine and Wimbledon deliver biggest boost British supermarkets sales in four years

British supermarkets reported a sharp increase in sales in the first weeks of the summer, as Britons made the most of the hot weather and of the bonanza of sporting events.

According to data released by market research group Nielsen, in the four weeks to 15 July, the amount spent on groceries in UK supermarkets jumped 5.1% year-on-year, the highest annual rise on rate for over four years.

The week ending on 24 June alone saw sales surge 7.1% from the corresponding period 12 months ago, largely thanks to the warm weather that swept through Britain until the end of last week.

The summer sunshine drove sales of ice cream and alcohol mixers up 45% and 44% respectively, while sales of cider and sparkling wines rose 19% and 17%, compared with a year ago.

For only the second time since July 2013 all the "Big Four" grocery retailers saw year-on-year sales rise, with Tesco's 2.8% representing the biggest gain among the industry's heavyweights. However, Britain's biggest retailer saw its market share drop from 27.7% last year to 27.3% this year.

Sainsbury's and Morrison's recorded sales increase of 2.2% and 1.7% respectively, while sales at Iceland grew 7.8%, the biggest rise of anyone outside the discounters. The latter, however, continued to outperform the market, with Lidl and Aldi registering a 17.5% and 15.2% jump in sales respectively.

In the week to 24 June, which coincided with the peak of the heatwave, sales of strawberries and cream rose 18%, whilst packs of strawberries alone increased 10% in the final week of Wimbledon.

The third Grand Slam tournament of the season was not the only sporting event that drove Britons to the supermarket, with the British and Irish Lions rugby tour, the women's cricket World Cup and the British F1 Grand Prix all thought to have contributed to an increase in sales.

"Various factors typically drive extra spend in grocery shopping – more disposable income, more promotions, peak events and changes in weather, and lifestyle," said Mike Watkins, Nielsen's UK head of retailer and business insight. "However, the first two have been falling in recent times which shows the impact that hot weather and big sporting events had on people's purse strings.

"This combination encourages shoppers to spend more, particularly on fresh foods and to use convenience stores more often. With the likelihood of eating and drinking outside also increasing people are more inclined to indulge and treat themselves."