A strong cold front will confirm winter's arrival over NSW, sending temperatures plunging for Sydney and delivering good snowfall for those able to make their own trek to the skifields.

For the harbour city, the mercury is set to drop to 4 degrees in some inland suburbs on Tuesday morning and 8 degrees near the coast, the Bureau of Meteorology said.

"It will feel definitely very cold," Scott Morris, a meteorologist with Weatherzone, said. Stiffening breezes will add a chill, so conditions will certainly "feel like winter", he said.

Temperatures will struggle to get far above the mid-teens across Sydney on Tuesday, and will likely remain below 20 degrees at their maximum for the rest of the week.