Schools have been closed, flights delayed and commuters are facing hazardous road conditions after heavy snowfall last night.
The north of England has been blanketed, with as much as 10cm of snow reported on high ground.
More than 50 schools in Oldham, Greater Manchester, 28 in West Yorkshire and eight in Leeds have been closed.
Heavy overnight snow in East Lancashire also led to the closure of up to 50 schools, with the Hyndburn, Burnley, Pendle and Rossendale areas most affected.
The Met Office has warned motorists to allow extra time for journeys because of icy conditions on the roads.
Weather warnings were issued for Northern Ireland, north Wales, northern and western England and Scotland as a frontal system came in from the Atlantic.
By the early hours of Friday just over an inch had fallen across high ground in northern England.
Similar snowfall was recorded at Leek in Staffordshire and Shap in Cumbria, and several A roads were closed over the high Pennines in south Yorkshire.
Leeds Bradford Airport was earlier forced to close as crews worked to clear the runway, after 5cm of snow fell overnight.
Flights resumed at 9am, but further delays were expected.
A spokesman said: "There are a number of delays which will be cleared by mid-morning. From our perspective the airport is now open for business."
Strong, north-easterly winds and wintry showers in many places will ensure temperatures remain below normal at least until the middle of next week, the Met Office said.