Olympic spectators are bracing themselves for the return of yet more wet weather on Sunday.
Forecasters say there will be heavy showers across central and east London, with hailstones also a possibility, following several days of sunshine and high temperatures.
The change in weather follows the wettest April and June on record and a rainy start to July.
Sports fans visiting the Olympic Park in Stratford, east London, can expect a dry and sunny start to the day, before the clouds start to build up, forecasters said.
Paul Mott, of MeteoGroup, the weather forecasting division of the Press Association, said: "There will be some showers around in the afternoon, and some of them look like being quite heavy.
"It looks like there could be some thunder and even hailstones. It's also going to be a fairly cold day compared to recent days, with highs of 20 degrees.
"Although there will be a lot of rain around, we're not expecting the day to be a washout, and it looks like we'll see a return to drier conditions on Monday."
Other Olympic venues are also forecast to be hit by adverse weather, with the Met Office predicting heavy showers at Wimbledon, where the tennis event is taking place, from around 1pm and lasting through the afternoon.
Elsewhere, the Archery at Lord's Cricket Ground and the fencing and judo at the ExCel Centre will be affected by heavy rain in the afternoon, the Met Office said. Meanwhile the cycling event will experience some lighter rain.
The Met Office also forecast heavy rain from around 10am at Eton Dorney in Buckinghamshire where the rowing competition is being held, and similar weather at the Lee Valley White Water Centre in Hertfordshire for the canoe slalom.