A low pressure system over the Tasman Sea has swept north bringing cold air across the region, with temperatures in some parts of NSW plumetting to five to seven degrees below average, according to the Bureau of Meteorology.

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"We have seen a very nice cold blast of air from the southern realms over the course of the weekend," BOM meteorologist Helen Reid said.

"A cold front moved through and brought some snow, predominantly to Victoria, but there was a little bit of a dusting on the Snowy Mountains as well."

Dr Reid said by the time the air passed over Victoria the air was so dry that the "apparent temperature felt lower than what the thermometer had on it".

At 6am Monday it was 10 degrees in Wollongong, though the BOM forecast it would have felt like 4.4 degrees.

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The BOM predicts by mid-week to heat up again, with temperatures around 26 for Wollongong, before a sharp cold front returns with frost and possible strong winds for the weekend.

It comes as the national weather agency released their three month climate outlook, which somewhat contradicts the arctic spell from recent days.

May to July maximum temperatures are likely to be warmer than average while rainfall is likely to be below average, the outlook suggests.

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"The climate outlook is an average over course of the next few months, so within that we will have a couple of days that will be cold and a couple of days that aren't so cold," Dr Reid said.

"There will be possibly less snow than you've seen in previous seasons because in general it will be warmer, but there will still be cooler periods in there as well."

She said the weekend was no start to the ski season, as it is quite normal to get a "dusting or two" of snow in April and May.