Weather warnings were issued after forecasters said there was a “real chance” of snow blanketing Britain in weeks.
The yellow alert warned the south could be hit with up to two inches of rain in just three hours from 1pm on Saturday.
Gusts of wind up to 65mph will accompany the lashing rain in some places.
Delays to road, rail, air and ferry transport are likely, the Met Office warned.
There is also a risk of short-term loss of power as well as spray or flooding on roads.
The Met Office added: ‘It’s likely that some coastal routes, sea fronts and coastal communities will be affected by spray and/or large waves.”
They also warned some homes may become flooded and transport links could face disruptions.
Parts of the UK on Friday were hit with heavy rain and winds as cars facing flooded roads in Putney, south west London.
Visitors to coastal areas have been warned about potential large waves on beaches which could wash them out to sea.
Travellers have also been advised journey times over the weekend could be longer.
Met Office Operational Meteorologist Dan Stroud said Saturday and Sunday will bring “persistent and at times heavy rain likely to move northeast across the UK”.
He said: “Winds strengthening in the south and east late Saturday afternoon and evening with coastal gales, gusting to 60-70mph along the south coast in places.
“The area of organised cloud and rain, locally heavy is expected to clear north and east on Sunday but may persists across the far northeast of Scotland for much of the day were it will remain windy for much of the day, again with coastal gales.”
On Sunday, frequent showers combined with hail and thunder are expected with unsettled weather predicted in southern areas until Tuesday.
Meanwhile, senior meteorologist at the Met Office Greg Dewhurst previously warned snow could be on the way within weeks.
He told the Mirror: “We’re now entering the time of the year when the change in conditions becomes really noticeable.
“As we enter October it certainly will get colder. Although snow is not forecast imminently, there is always a real chance in the weeks ahead. It is not uncommon at this time of the year.”