Environment Canada says residents in parts of Prince Edward County to Kingston, Ont., should prepare for an intense snow squall expected to develop over Lake Ontario Thursday night bringing extremely dangerous travel conditions.
The weather is likely to change from clear skies to heavy snow within just a few kilometres Friday morning, and again Friday night into Saturday.
The weather agency says local snowfall accumulations of 20 to 30 cm are likely by Sunday morning.
Higher amounts are possible in persistent snow squalls.
Environment Canada warns visibility may be reduced to near zero in heavy snow and blowing snow.