The cold snap is expected to ease after fierce winds and icy conditions blasted Sydney and other parts of NSW on Wednesday.
Temperatures are forecast to reach 16C in Sydney and continue to rise until the weekend.
"The wind chill factor made it feel extremely cold (on Wednesday)," Bureau of Meteorology spokeswoman Olenka Duma said.
"Although temperatures will be only slightly warmer by the weekend, it won't feel quite as cold because there won't be as much wind."
Wednesday's wild weather turned fatal after a motorist died when a tree fell on his car in strong winds near Wollongong on the state's south coast.
The man, 28, was travelling on the Princes Motorway near the Picton Rd overpass on Wednesday morning when the 20-metre gum tree fell and crushed the cab of his ute, trapping him, police said.
An SES spokesman said winds had reached up to 100km/h around the Illawarra region at the time with crews attending numerous felled trees and fallen branches.
Winds were expected to ease up by Thursday, with the mercury forecast to rise into the low 20s by Monday.
Since Tuesday night, the NSW SES has received more than 500 calls for help from Sydney, Illawarra and Southern Highlands regions as winds brought down trees and power lines.
More than 18,000 power outages were reported across Wollongong and the Southern Highlands on Wednesday with Endeavour Energy emergency crews managing to restore power to most homes and businesses by Wednesday night.
Coastal authorities have meanwhile warned swimmers and rock fishers of "deceptively powerful" surf conditions stretching up the coastline from Ulladulla to Tweed Heads, with a long swell period to intensify through Thursday.
The National Parks Service of NSW is recommending people consider postponing country travel while police have also urged motorists to delay travelling through Jindabyne in the state's alpine region, as roads remain treacherous with ice and snow.
