Much of NSW would have felt like they spooned a hot water bottle last night.
Sydneysiders especially would be forgiven for thinking they'd slept with the heaters on as the city sweltered through one of the warmest September evenings on record.
Temperatures in the city did not dip below 26 degrees on Saturday evening, an event weather experts describe as "phenomenal".
"We expect lots of variability for this time of year, but not quite to these extremes," Bureau of Meteorology senior meteorologist Jake Phillips said.
Sydney's overnight minimum temperature was 25.7 degrees, beating the September record by 3.7 degrees.
This weekend's temperatures are warmer than record minimums usually recorded in typically warmer months like October, November, March and April.
The city is expecting a maximum on Sunday of 33 degrees. It was 28 degrees by 6am.
The heat comes just over a week after Sydney notched 33.8 degrees, the hottest day so early in the warming season, and not far shy of the record high for a September day of 34.6 degrees set in 1965.
September records also tumbled in northern NSW and parts of the Hunter Valley on Saturday where it was more than 12 degrees warmer than recorded averages.
The heat will continue on Sunday. Gosford reached 30.5 degrees at 6.01am after dipping to 19.8 degrees overnight.
Newcastle is set for a maximum temperature of 32 degrees. By 7am it was already 28 degrees.
The NSW Rural Fire Service has issued a total fire ban throughout NSW on Sunday stretching from the Illawarra to the Queensland border.
A fire burning in the area of the Hume Highway near Paddys River remains out of the control yet the highway is open in both directions.
A westerly is expected to move through Sydney late on Sunday which will drop temperatures to about 15 degrees.
The high daytime temperatures are expected to remain with 26 degrees forecast for Monday and 23 on Tuesday before climbing again toward the end of the week.
