In the Dunedin region, tomorrow would start with possible morning frosts, but as the northerlies changed southwesterly, showers would develop and turn to snow in the evening.
The snow was expected to lower to about 400m in the Dunedin and Southland areas, and 300m in inland Otago.
The weather was expected to clear on Thursday.
The combination of low temps & strong winds will produce a low wind chill Wed & Thu.
MetService said it was a "significant weather event" for October and urged farmers to be prepared for the polar blast which may bring stress to livestock.