A cold weather alert has been issued for large parts of England, with the Met Office warning of heavy snow and health risks to vulnerable people.

The level 2 alert runs from 6pm on Sunday to 9am on Thursday across the North, Midlands, and central and eastern parts of England.

The Met Office says there is a 70% probability of severe cold weather, icy conditions and heavy snow, and has advised people in those regions to stock up on food and medicines to reduce the need to go outside.

London, the South and South West are covered by a level 1 alert – warning people to stay vigilant.

Scores of flood warnings remain in place following heavy rain that has left roads and fields underwater and threatened homes.

Further downpours are forecast over the weekend and it will remain windy – while turning colder – as the mild air of recent weeks slips away and colder northerly air moves in.

Showers will increasingly fall as snow, especially across northern areas.

Sky News weather presenter Kirsty McCabe said: “Obviously there are more rain and wind warnings in place for the system moving through tonight and clearing tomorrow.

“Heavy rain expected in areas already hit by flooding.

“Then it’s a big change through Sunday into next week as jet stream plunges south, dragging cold air from the north across the UK.

“So it will be much colder, with significant wind chill and an increasing risk of winter hazards such as snow and ice.

“It is definitely one to watch on Sunday night into Monday morning for southern England, although confidence is low at this stage.”

On Friday morning, there were 90 flood warnings and 166 alerts in force across England, stretching from Devon up to Newcastle and Cumbria.

There were eight flood warnings in Scotland and seven in Wales.

In York, levels on the River Ouse were about 3.8m above normal and predicted to rise further overnight.

Shrewsbury in Shropshire was another of the areas affected, with the council saying flooding was disrupting traffic in the town centre.

Shaun Jenks said on Twitter there was “gridlock” in the town and that it was “now at the mercy of the River Severn” as flood defences were being put up.

Meanwhile in Keynsham, Somerset, fire crews had to rescue people from submerged vehicles on Old Bristol Road on Thursday.

And on Friday, the local football club posted images of their pitches looking like swimming pools and joked about needing a water polo team instead.

The Environment Agency’s Mark Garratt advised people to check their local flood risk, stay away from swollen rivers and not drive through floodwater.

Mr Garratt said: “The Environment Agency is monitoring flood levels, operating flood gates and barriers at locations across the country, and ensuring debris screens are clear from blockages to ensure communities are better protected.”

Andy Wall, from Natural Resources Wales, said there was “widespread travel disruption with flooding of low-lying land and roads”.

He added: “Given the rainfall being forecast by the Met Office into the weekend, we would expect to see rivers full again, and are quite likely to see flooding onto floodplains, farmland, minor roads, and we could see some property flooding, particularly in isolated communities in low-lying areas.”

Rod Dennis, from RAC Breakdown, said driving in floodwater was “never worth the risk” as it can endanger passengers and potentially “cause catastrophic damage” to vehicles.

“We encourage all drivers to turn around and find another route if they encounter deep standing water,” he said.