Sydney residents have shivered through the city's coldest April morning in five years as the most intense cold front of the season sent temperatures plunging across much of eastern Australia.

The overnight low of 10.2 degrees felt a lot closer to 7 degrees with the wind chill factor. Those up early on Saturday for school sport and other outdoor activities will want to rug up, Brett Dutschke, a senior meteorologist with Weatherzone said.

"Tomorrow morning will have a similar wind chill in the air, with the wind reasonably brisk," Mr Dutschke said.

Temperatures were as much as 10 degrees below average in northern parts of NSW and Queensland, with a slew of towns such as Toowoomba and Longreach recording their coldest April temperatures in 18 years, he said.