Source: Sharecast
The average price of a home coming to market fell by 0.6%, or £2,113, in June to £376,191, leaving prices 0.5% lower than a year earlier.
Rightmove said the decline was unusual for the time of year, noting that June has typically delivered modest price growth of around 0.1% over the last decade.
"It’s unusual to see a price fall of this size in June, as we would normally expect to see modest price growth at this point in the year," said Colleen Babcock, property expert at Rightmove.
She said a combination of "wider economic uncertainty, the timing of the May bank holiday and unusual heatwave, and the high number of homes on the market" had helped bring forward the traditionally quieter summer market.
The number of homes available for sale remains at historically elevated levels, increasing competition among sellers and putting pressure on asking prices. Rightmove said more than a third of newly-listed properties fail to sell.
"In this kind of market, sellers need to work harder to attract attention," Babcock said. "Setting a competitive asking price from the outset is key."
Despite softer pricing, transaction activity remained relatively resilient. Buyer demand during May was down 10% year-on-year, while sales agreed fell 6%, though Rightmove said activity remained broadly in line with recent years.
The property website also reported a modest improvement in mortgage affordability, with the average two-year fixed mortgage rate easing to 5.07% from 5.18% a month earlier.
Babcock said buyers were becoming increasingly selective. "With more homes to choose from and higher borrowing costs, buyers are deliberating more and taking longer over their decisions."