Clouds gathered over London on Friday but forecasters said there was only a small chance of a shower during the Olympics opening ceremony at 9pm.
"It will be rather more cloudy than of late with showers across the south east through the day, some of them heavy," Britain's Met Office said in a statement.
"These are expected to clear during the evening to leave it mainly dry for the opening ceremony.
However, there remains a small chance of a shower lingering in the evening, although there is a good chance it will be mainly dry."
London had enjoyed hot temperatures in recent days.
More than 10,000 athletes from over 200 countries are competing in the Games.
The star studded opening ceremony will be attended by an estimated 80,000 people - including monarchs, presidents and prime ministers.
It will be watched by a TV audience of over one billion people.
Watch live on RTÉ Two and RTÉ.ie from 8.30pm
