Trading across the whole of June was also well up on expectations, with retail analyst SalesOut reporting an 8.1% increase over last year's sales in the independent sector.
Hiral Patel, who owns a Londis store in Surrey, said the above average temperatures had helped his takings to climb by more than £300 compared with the previous week.
"Soft drinks, ice cream and ice cubes have been flying; it's absolutely fantastic," he said. Hiral also reported an additional £100 in tobacco sales as customers held impromptu garden parties.
Retailers located by the sea or in holiday locations were the big winners as temperatures soared in the last week of the month. Stuart Blundon of Bognor Regis said his sales were up 300% on the previous week.
"Bottled water has been the top seller," he said. "I've gone from selling one case a week to 10. I just can't get it on the shelves fast enough." A supply blip with one major bottled water brand earlier on in the month was quickly resolved, he added.
Nisa retailer Derek Edwards who owns a store next to a holiday park in Mid Wales also said his sales had "gone through the roof".
"The hot weather coupled with the fact that more people are holidaying at home this summer has led to a 10% jump in my profits compared with this time last year," he said. "Boosts like this are fantastic news for retailers like us who suffer from a downturn in the winter months. If it carries on like this, we'll be sitting pretty by the autumn."
SalesOut commercial director Steve Collins said that the hottest June since 2006 had also seen consumers shopping locally to make the most of their leisure time in the sun.
However, the heat hasn't been good news for everyone. Independent retailer Jill White who owns the Little Stour Farm Shop in Canterbury said that "extortionate" electricity bills had forced her to reduce the number of freezers in her store.
1. Bottled water
3. Handheld ice cream
4. Ice cubes
5. Ice cream tubs
7. Tobacco products
10. Prepacked sandwiches