The drop followed a 0.4% in August, and was mainly driven by online retailers, which were hit hardest with a 2.2% fall in sales volumes, according to the Office for National Statistics.
Non-food stores sales volumes fell by 1.9% last month, which retailers attributed to continuing cost of living pressures, alongside the unseasonably warm weather reducing sales of autumn-wear clothing.
This was partly offset by a 0.2% rise in food stores sales volumes rose by 0.2%, following a rise of 1.4% in August. Automotive fuel sales volumes also rebounded from a 1% drop the previous month, rising by 0.8%.
UK inflation remains steady at 6.7% in September
In the three months to September, sales volumes were down 0.8% compared to the previous three months, although the value of those sales were up 0.3%.
"Online retailers have been hit hardest, but that will be no relief for the high street. The trend is put down to the record-breaking warm weather in September, and could easily go into reverse," said Nicholas Hyett, investment manager at Wealth Club.
"With evidence of higher prices in these numbers too, there is a lot of gloom where the UK shopper is concerned."
Last month, UK inflation remained steady, with prices rising 6.7% year-on-year and matching the previous month's figure. The underlying data showed that food price inflation was slowing, but petrol prices continued to rise.
UK wage growth eases at 7.8% as job vacancies fall
Neil Birrell, chief investment officer at Premier Miton Investors, said that it was not surprising to see the consumer sector under pressure "given what has been thrown at it".
However, he noted that this data will be seen as good news by the Bank of England, although arguing that it is unlikely to be a "major factor" in their policy decisions.
Hyett said that after September's higher than expected inflation numbers, weak retail sales may help convince interest rate setters that "they can afford to wait before moving rates up again".
Consumer confidence tumbles
As consumers contend with higher prices, mortgage and rental costs, the closely watched UK consumer confidence survey by GfK registered its biggest month-on-month drop in more than three years in October.
The GfK Consumer Confidence Index decreased four points to -17 in October, falling for the third month in a row as higher interest rates hit households.
UK consumer confidence and retail sales receive late summer boost
Joe Staton, client strategy director GfK, said that after six-months of "robust recovery" in the first half of 2021, UK consumer confidence has taken "a turn for the worse" with all vital signs weakening.
"For two consecutive months five sub-measures have decreased and the headline score has dropped three months in a row. The sharpest concern is how consumers see the future economy with this collapsing ten points this month just as it did in September," he said.
"Against a backdrop of cheerless domestic news - fuel and food shortages, surging inflation squeezing household budgets, the likelihood of interest rate rises impacting the cost of borrowing, and climbing Covid rates - it is not surprising that consumers are feeling down-in-the mouth about the chilly winter months ahead."