The latest British Retail Consortium-KPMG survey showed that total retail spending lifted by 1.4% compared to a year ago, while like-for-like sales rose by 0.5% last month. This follows two flat months in April and March.
Clothing retailers drove high street sales with a strong performance in May on the back of brighter weather, following a poor month in April that saw unseasonable conditions dampen shoppers' interest in new spring and summer ranges.
Children's clothing and footwear were the standout fashion categories, as parents prepared for the half-term school break.
BRC chief executive Helen Dickinson said: "Clothing made a big comeback this month after suffering declines in April. This appears to be due to consumers waiting for just the right moment before embarking on their pre-summer spending.
"However, with signs that the UK's economy is slowing, it's unlikely that this is the beginning of a complete reversal of fortunes.
"The uncertain outlook means that customers will remain cautious with their spending, therefore we expect sales figures to remain volatile for the time being."
Last week, the UK's powerhouse service sector inched ahead showing a reading of 53.5 in May, up from 52.3 in April when activity rose at its slowest pace for more than three years, according to the closely-watched MarkitCIPS services purchasing managers' index.
This follows revised figures from the Office for National Statistics in April that showed UK gross domestic product grew by 0.4% in the first three months of 2016, down from 0.6% in the fourth quarter of last year.
IHS chief UK & European economist Howard Archer said: "A relatively resilient BRC survey for May would lift hopes that the consumer will make a reasonable contribution to UK gross domestic product growth in the second quarter, thereby limiting the likely further slowdown influenced by heightened uncertainties ahead of the EU membership referendum."
David McCorquodale, UK head of retail at accountants KPMG, added: "With a summer of sport kicking off in June and festival season getting under way, retailers will be hoping that the feel good factor coupled with a dose of summer sunshine will keep the tills ringing over the summer months."
Also, credit card firm Barclaycard noted that consumer spending rebounded in May after two months of weak growth, rising 3.6%, as spring weather and the bank holiday boosted spending on the home, clothes and entertainment.
A strong performance from garden centres, DIY stores, fashion and pubs and restaurants drove sales as shoppers took full advantage of sunnier weather, said a survey from the credit card firm.