Waitrose has experienced a dramatic sales slowdown this summer, according to its publicly released figures.

In the five weeks to 19 July, Waitrose sales growth, including petrol, averaged just 0.64%, and for two of those weeks sales growth was negative, data from its weekly trading updates shows. By contrast, in the previous 20 weeks, sales growth averaged 5.5%.

Analysts said the weaker performance should not raise alarm yet. They said Waitrose had come up against a period last year when trading had been particularly strong thanks to the weather. “The issue is the tough comps from last July when the heatwave was driving a ton of picnic and barbecue business and like-for-like sales were over 10% up,” said independent retail analyst Nick Bubb.

Waitrose also blamed tough comparatives. “Our recent figures have been no surprise as we’ve been trading against an exceptional period last year, where strong promotional activity resulted in double-digit growth,” said a spokeswoman.

On Friday (1 August), Waitrose revealed growth had picked up again in the week to 26 July, with sales up 6.7%.

But Shore Capital analyst Clive Black warned Waitrose was not immune to the wider industry issues of slow growth and price deflation. “The UK grocery trade is especially weak at the moment - note how the Ocado run rate was materially slower in its most recent trading update too, while Iceland has seen falling sales in recent times,” he said.

Aldi is likely to soon overtake Waitrose as the sixth-biggest food retailer in the UK. Waitrose’s market share is currently 4.9% - just 0.1 percentage points ahead of Aldi, according to Kantar data (p6). In the 12 weeks to 21 July, Kantar said Waitrose sales rose 3.4%, better than all its bigger rivals but well below Aldi’s 32.2% growth.