Widespread snow across the UK overnight has hit transport links, with police forces in the worst-hit regions urging people to avoid non-essential road travel.

The wintry snap dubbed the “mini beast from the east” brought up to 15cm of snow for parts of the south east overnight as temperatures plummeted below freezing nation-wide.

The Met Office has weather warnings in place for more snow and ice for most of the country, with some areas of south west England and Wales likely to see up to 25cm of snowfall on Sunday.

Highways England has issued a severe weather alert for snow, with motorists advised to check road conditions before setting off, Traffic Wales warned of adverse conditions on some routes and Traffic Scotland urged road travellers to use caution in eastern parts of the country.

On the rail network CrossCountry was experiencing “significant problems” due to adverse weather, Great Western Railway cancelled services between Exeter and Barnstaple until midday and South Western Railway cancelled some morning services to test the track after a combination of high winds and snow.

Meanwhile Bristol Airport said it had been forced to close its airport until midday “despite all the efforts of our snow clearing team”.

Heathrow Airport said “extreme wintry weather” was expected, adding: “In preparation, we’ve worked with our airlines to consolidate Sunday’s flight schedule, moving passengers on to fewer flights.

“This decision enables us to provide more certainty to passengers around departing flights, whilst ensuring safety and service standards despite the challenging conditions.”

Gatwick Airport said it had seen snowfall overnight, although flights were arriving and departing as normal.

Stansted Airport and Luton Airport also advised passengers to check with their airlines.

Met Office meteorologist Becky Mitchell said: “There will be tricky travel conditions and disruption and we want to make sure people are aware that they need to check before they set off.

“Many places have seen some snow overnight and we’ve got some showers pushing across eastern Scotland, much of northern England and quite a few parts of Wales.

“Elsewhere it’s going to turn dry and brighter, however the main focus for snow later today will be in the south west.”

Avon and Somerset Police, North and South Wales Police and Humberside were among the forces asking motorists to avoid non-essential road travel.

Wattisham in Suffolk saw 15cm of snow fall overnight Saturday and into Sunday morning, while Nottingham awoke to a covering 13cm deep.

Shetland saw the coldest temperature overnight, with a low of minus 5.8C (42F), although frost was widespread, with Okehampton in Devon seeing a low of minus 4.7C (40F)

The M25 was gridlocked on Saturday between junctions 17 and 18 anti-clockwise after an air ambulance attended a crash, while a collision also closed the westbound junction of the M4 in Wiltshire between junctions 14 and 15.

Meanwhile, 11 people were rescued or made their own way to safety after two rowing boats and an accompanying safety boat capsized in the River Stour in Bournemouth.

Local media reported that most of the group were teenage girls, along with one adult in the safety vessel.