A series of cold fronts passing over southeastern Australia will drag a mass of frigid Southern Ocean air over NSW until Saturday.

This frontal precession is more typical during early spring than November. However, a negative phase of the Southern Annular Mode (SAM) is responsible for this week's chilly weather pattern.

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The SAM is an index that measures the north-south displacement of a westerly wind belt that surrounds Antarctica, flowing between Antarctica and Australia throughout the year.

When the SAM is negative, these westerly winds shift towards the equator, which can cause cold fronts to become more active over southern Australia.

This week's flurry of cold fronts over southeastern Australia is a consequence of a negative phase of the SAM, which has been occurring since mid-October.

The impending cold weather should cause temperatures to drop low enough for snow to settle on highland areas of NSW later in the week.

Snow could fall to 800-1000 metres in southern NSW when the coldest air arrives on Friday night and Saturday morning.

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There's even a chance of a few snow flurries in elevated areas of central NSW on Friday night or Saturday morning, although this depends on how much moisture makes it this far north.

Showers, thunderstorms, small hail and raised dust could also be a feature during the next several days.

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