Storm Callum will relax today after he has killed two people.
The southeast, which has escaped the torrential rains of the last 48 hours, will live overnight in sultry conditions with high teens temperatures.
But the rain that plagued West England will find its way east during the day and weaken, meaning that there will be a "reversal of wealth" in the afternoon, the Met Office said.
"The areas that have seen most of the sunshine in the last few days will then be under the cloud, sometimes with spotty, light rain and drizzle," said meteorologist Simon Partridge.
"The areas further west that have seen huge amounts of rain eventually become drier, brighter, and sunnier days that will develop until the end of the day," he added.
Scotland and Northern Ireland should be largely dry and clear until Sunday.
As Sunday dissolves into Monday, clouds and uneven rainfall in the southeast will continue north and west with generally clear, dry conditions.
"It's a cool start for many parts of the UK on Monday, and in fact it's a dry, beautiful and sunny day for much of the UK," said Partridge.
Clouds and uneven rain will remain over the southeastern corner of the UK until the early hours of Tuesday, with a drier, cooler view expected for the week, he added.
Storm Callum caused travel exhaustion and flooding as rivers burst their shores and power supplies to many in the western parts were destroyed on Friday and Saturday, with South Wales being the worst affected region.
A man died following a landslide on Saturday near the village of Cwmduad in Carmarthenshire, West Wales.
The victim, whose age was not specified, died at the point on the A484, said Dyfed-Powys police.
The east and southeast escaped the anger of the storm and enjoyed largely sunny, warm conditions.
Donna Nook in Lincolnshire reached 26.5 ° C on Saturday, making it the warmest October day in seven years.
Three-day weather forecast:
Today (Sunday): It will be a largely cloudy and wet morning in the UK, with heavy rain or rain for much of England, Wales and Scotland.
The rain will clear through the day to the east, first duschig, but then brighter and cooler with the sunshine behind it. A largely dry and beautiful day for Northern Ireland.
Tonight (Sunday night): A rather wet and cloudy night in the extreme southeast of England with rain everywhere. Elsewhere it will be dry most of the night, with clear slogans in the central and western parts.
North-West Scotland will see rain showers and it could get wet until the wee hours of the morning.
UK Outlook (Monday and Tuesday): It will rain Monday in the far southeast of England. North West Scotland will see showers everywhere. Elsewhere, it becomes largely alright and dry with bright sun rays.
On tuesday we face storms, with storms in northwest Scotland and rains for many. Dryers in central parts.