The hot start to November may be a taste of the summer to come with meteorologists watching a Pacific Ocean that is being primed for an El Nino event.

Sydney backed up Friday's scorcher with another day in the mid-30s across the basin before a weak cool change arrived on Saturday afternoon.

Early season heat in Sydney - and the growing prospect of an El Nino. Credit:Nick Moir

According to Weatherzone, NSW averaged 34 degrees on Friday, the hottest this early in the warming season in at least two decades.

"In the past 20 years, the previous earliest in the season the state had got this hot was the 12th November, in 2009," Brett Dutschke, senior meteorologist with Weatherzone, said.