"Significant accumulations" of snow are expected for Hull and East Yorkshire on Sunday and Monday, according to the Met Office.
Forecasters say up to 10cm could fall - with more on higher ground.
A severe weather warning issued yesterday for Saturday night and Sunday morning has now been extended to Monday.
The worst of the snow is expected in the early hours of Sunday and on Monday afternoon.
Temperatures are set to fall as low as -5C as the mild weather of the first half of January makes way for a big freeze.
Alexi Boothman, a forecaster with MeteoGroup, said: "Temperatures will fall over the weekend, and in many places, even during the daytime, we won't see more than a degree or two above zero.
"From overnight tonight we can expect to see wintry showers arriving down the east coast, driven by cold easterly winds."
Hull City Council said its gritters were ready to deal with snow and ice and would work "24/7".
There are 420 new grit boxes throughout the city which can be used on any public highway, but are not for private residential use.
Councillor Martin Mancey, portfolio holder for environment and transport, said: "The safety of drivers, pedestrians and residents is a top priority for us.
"We have a committed and dedicated team that work 24/7 to ensure the main traffic routes, pedestrian and shopping areas are as clear and as safe as possible."
