The Bureau of Meteorology is forecasting snow above 800 metres on Monday evening, with falls expected to the south, west and east of Lithgow Bathurst.

According to the bureau's MetEye website, snow could start falling around west of the region late afternoon on Monday, with the footprint to grow significantly in the hours after that.

By 10pm we can expect widespread falls stretching to Orange and Mount Canobolas in the west.

The snow is forecast at the beginning of a week where lows are expected to clear below zero by Friday.

There is a slight chance of rain on Monday evening.

Winter will hit with a vengeance on Tuesday when the bureau is forecasting a maximum of seven degrees with a morning shower or two, and there is forecast top of 12 on Wednesday.

Cloudy conditions will return on Thursday and Friday.