The Met Office has issued a warning for severe flooding in north-west England.
Heavy rain is expected in Blackburn, Blackpool, Cumbria, Greater Manchester, Lancashire and parts of Yorkshire from Thursday night until Friday morning.
Some homes and businesses could be submerged in water, with nine flood warnings in force across the region.
Several warnings have been issued for the River Wyre and the River Ribble.
Bus and train services are likely to be disrupted by flooding, according to the Met Office.
A spokesman for the organisation said: "Further persistent rain, heavy at times, is likely until the early hours of Friday morning.
"20 to 30 mm rain is likely to accumulate, and with ground already saturated, some flooding is possible in places. The rain will clear eastwards early on Friday morning."
A flood warning for the River Wyre states: "River levels are rising steadily on the River Wyre due to heavy rainfall.
"This Flood Warning has been issued because flooding is expected overnight on 30/12/2021 between 10:00 PM and 03:00 AM on 31/12/2021.
"Areas most at risk include the area of St Michaels that is to the south of the River Wyre.
"Flooding is expected at the area of St Michaels that is to the south of the River Wyre between 10:00 PM on 30/12/2021 and 03:00 AM on 31/12/2021.
"River levels are expected to remain high overnight. We will continue to monitor levels closely.
"Avoid using low lying footpaths and any bridges near local watercourses and do not attempt to walk or drive through flood water.
"Start acting on your flood plan if you have one."
Similar flood warnings have been issued for other parts of the River Wyre and the River Ribble.
The Environment Agency has a total of 56 flood alerts in force in England, with many active in the north-west.
It comes after forecasters predicted New Year's Eve could become the warmest on record.
The Met Office put this down to warm air from the Azores and the central Atlantic billowing into the UK.
It means the record for the highest temperature on New Year's Eve in the UK - 14.8C at Colwyn Bay in North Wales in 2011 - could be broken.
The mild temperatures are expected to last until the end of the week, before dropping to around 6C in Scotland and the north of England, and around 9C in the south of England from Bank Holiday morning.
Craig Snell, forecaster with the Met Office, said the milder temperatures were "all to do with the wind direction".
Mr Snell said: "I think people will continue to feel how mild it is over the coming days.
"We are keeping a close eye on the New Year's Eve weather, because that record (14.8C) is quite under threat."
