Drenched London 2012 spectators had a true taste of British summer after the heavens opened above the Olympic Park.
There has been heavy rain over the east London site, with thundery downpours expected later today, forecasters said.
A number of open-air events across the capital, including tennis, archery and beach volleyball, could see rain clouds loom over the arenas.
Spectators hoping to catch a glimpse of the women's cycling road race could also encounter the wet weather.
Although there has been some short showers at the Stratford site since the Games began, visitors to the competition have not yet endured a heavy rainstorm.
Meanwhile, forecasters said they could not rule out showers in Weymouth, where thousands have gathered to watch the sailing.
The mercury is not expected to reach more than 20C in London today. It is about 17C in the Olympic Park - which is below average for this time of year.
Aisling Creevey, forecaster with MeteoGroup, the weather division of the Press Association, said: "Heavy thunder showers are approaching London from the south west.
"A line of showers came up from the Channel in the last few hours or so. Everywhere in London is at risk of showers today.
"I would not completely rule out showers in Weymouth, at the moment there is a band of showers travelling eastwards towards Weymouth but it might not reach it."