Severe rain could cause flooding in Northern Ireland and parts of Scotland today, the Met Office has warned.
A yellow weather warning has been put in place by forecasters.
The warning is in place until midnight covering the whole of Northern Ireland and the east of Scotland.
Grampian, Highlands and Eilean Siar, Tayside and Fife are among the areas affected.
Experts say there is a small chance of homes and businesses being flooded, while travel disruption is possible as a result of the weather conditions.
As well as being wet, parts of the UK are likely to be windy at times, with showers moving into eastern parts of the country.
Alex Deakin from the Met Office said: “Low pressure will dominate through the weekend and into next week and churning around this low pressure, we're going to see slow moving weather fronts.
“A few showers over parts of eastern England, they could be quite lively.
Some thunderstorms are possible, but they will be hit and miss here, so not to be relied upon if you are desperate for some rain.”
The wet weather will continue to push east on Sunday, with a risk of thunderstorms and the likelihood of stronger winds.
Eastern England will enjoy a dry start to the day but rain is expected to set in by the evening.
Despite the windier and wetter conditions, temperatures are set to remain above average for the time of year and it will feel warm in the sunshine.
The unsettled weather is set to continue throughout next week, when further thunderstorms are a possibility.
UK forecast for the next 5 days
Heavy rain at times in west - sunshine and showers in east
Today: Heavy rain will affect parts of Northern Ireland, western Scotland and some other western areas. Sunny spells in central and eastern parts, where turning warm, before scattered showers develop - these possibly heavy with a risk of thunder, mainly in the north.
Tonight: Further rain, some heavy, in the north and west, with a few showers elsewhere. Windy in the north and possibly south-western areas later.
Sunday: Spell of wet and windy weather moving north across western parts, with further spells of rain in the north and later the south-west. Elsewhere, sunny spells and a few showers.
Outlook for Monday to Wednesday: Very unsettled with spells of heavy rain and showers for all parts of the UK. Some drier and brighter spells are possible at times, especially in the east.
