Temperatures should remain slightly higher than average for late October, with the mercury set to reach 16 degrees.
Flooding is possible in parts of London and the southeast on Monday and in areas of Wales and north west England on Wednesday, according to The Environment Agency.
Rivers and surface water could overflow putting land, roads and homes at risk with possible disruption to travel.
Six flood alerts are currently in place.
The Met Office said to expect wet and windy weather throughout the rest of October with heavy downpours for many.
“Through this period, Atlantic systems will move in from the west, bringing unsettled and windy conditions,” a spokesperson said.
More rain developing for some tonight, before a mixture of bright spells and blustery showers tomorrow ☔️🌥️
Nick Miller has the forecast 👇 pic.twitter.com/uags51xfBz
— BBC Weather (@bbcweather) October 23, 2021
“On Thursday, the northwest may start mainly dry with a few showers, but turning wetter later as some rainbands becoming slow-moving, while the southeast is more likely to see dry and fine conditions.”
London, the south and southeast will benefit from the driest conditions with lighter gusts and overnight fog towards the end of the month.
Meanwhile the west and northwest will take the brunt of the rain with 20 to 40mm widely expected and up to 90mm falling over the Scottish hills.
The weekend will see a band of rain sweeping southeastwards across England and Wales.
A spell of persistent and heavy #rain will set in across parts of southwest and central #Scotland on Saturday evening through until Sunday morning ☔
20 to 40 mm is expected quite widely, with perhaps as much as 70 to 90 mm falling over the hills
Stay #WeatherAware ⚠️ pic.twitter.com/bTGUGYHfYj
— Met Office (@metoffice) October 23, 2021
A mix of sunshine and heavy blustery showers will crop up behind the rain.
On Monday, showers will scatter parts of the west while the north is set to remain windy.
Sunny weather will return for the rest of the nation with some showers too.
Forecasters predict Tuesday to be drier with rain developing later on in the northwest, western Scotland and Northern Ireland.
This will continue into Wednesday while England and Wales will remain mainly dry but breezy.
On Thursday, low pressure from the west will bring more rain.
Temperatures are expected to stay stable throughout the week, with highs of between 15 and 17 degrees forecast for London over the coming days.