The Environment Agency has issued seven flood warnings and 37 alerts, with areas across Lancashire, West Yorkshire (EA), Cumbria and North Wales expected to be hit hardest.
It comes as the EA launched a flood awareness campaign which urges people to prepare for the worst.
Farmers Guardian’s weather expert Dr Simon Keeling said the jet stream had returned to the UK, bringing with it heavy rain and gusts of more than 60mph over northern England and southern Scotland.
In Wales, forecasters said rivers in Snowdonia were ‘swollen’ after up to 2.5in (63mm) of rain fell in 36 hours.
The Met Office warned the risk of flooding would persist through the start of the week as the water made its way through the river system.
Dr Keeling added: “Little changes as the week progresses, it stays mild with the highest risk of rain in the north and west, but drier in the east and south.
“Friday has our attention at the moment; it is likely to be a cooler day, windy once again and with rain or showers.
"There is the potential for some snow over northern hills and mountains, perhaps as far south as northern England.
“Just don’t let talk in the press of ’blizzards’ lead you to thinking there is something more severe on the way - at the moment there isn’t.
“Things probably then become milder and windier again into the weekend as temperatures rise once again."
It comes after a Met Office report warned the El Nino - caused by the warming of the Pacific Ocean - could bring floods and gale force winds similar to the winter of 2013.
The report said: “The risk of spells of windy or stormy weather is greater than usual. There is clear shift towards above-average rainfall.
"El Nino moderately increases the probability of increased frequency of Atlantic depressions crossing the UK and wetter-than-average conditions."
The EA has encouraged people to visit its advice pages at www.gov.uk/floodsdestroy and take simple steps to help protect themselves, their homes and their businesses from flooding.