Strong winds are also forecast, with a yellow weather warning in place for most of England until 7am on Thursday. The Met Office has warned of delays to road, rail, air and ferry transport.
It follows an alert issued for heavy rain for north-west and north-east England, southern Scotland, north-east Wales and the Yorkshire and Humber region, which runs from 8am on Wednesday to 11pm that evening.
Meanwhile north of the border there is a snow warning in place from 3am to 1pm on Thursday, covering most of northern Scotland.More news: Rihanna, Kim Kardashian call for justice for imprisoned sex trafficking victim
Heavy rain will accompany the strong winds with most places experiencing between 25mm and 50mm which could affect driving conditions.
"We expect widespread frosts and wintry showers in the north which could reach low ground, overnight temperatures will touch freezing or below quite widely with -5C (23F) possible further north".
"Over southern coastal areas and high ground gusts of 70 miles per hour are possible, particularly over the mountains of Wales and Moors of southwest England on Wednesday morning and afternoon and then around coastal areas of the southeast of England overnight into Thursday".
"Bus and train services will also probably be affected with journey times taking longer and flooding of a few properties is possible".