The Met Office has upgraded its weather warning for South Yorkshire from yellow to amber - with frequent heavy snow showers expected throughout the day.
Snow fell overnight and this morning, with snow settling on roads and pavements - causing traffic chaos on the roads.
Scores of schools across the county have also closed on safety grounds or because of staff unable to reach their classrooms.
This morning the Met Office said 'travel delays on the roads are very likely' and warned that stranded vehicles and passengers are possible.
It said some communities could be cut off by the snow, power cuts could occur and mobile phone signals could be affected.