Sydney has sweated through it warmest March night in 149 years and woken to a day of extreme heat.

Beaches and water parks were packed as temperatures climbed into the high 30s today in what felt like a return of summer.

The heat was expected to linger into the evening in Sydney, with 30 degrees forecast at 9pm before a welcome cool change about midnight.

Sydney heatwave Manly March 16
Manly beach was packed by early morning today. (9News)

“Today is the hottest day, and then it is the end – well, that is the hope,” said Bureau of Meteorology senior meteorologist Magda Gallos-Lorenc.

Last night was Sydney’s warmest march night on record, dropping to just 25.9 degrees at its coolest.

From Manly to Cronulla, beaches were busy early as the warnings rolled in.

“The heatwave season is not over yet. Summer is – heat is a silent killer,” NSW Ambulance associate director for emergency management Steve Vaughan said.

“Really goes for anyone, don’t be outside in the middle part of the day when it’s at its hottest.”

He said paramedics were braced to get about 3500 calls for help.

Sydneysiders swarm to the beach as autumn heatwave grips city

Heatwave Sydney
Temperatures across Sydney nudged to 35 degrees by 1pm. (Zoom.earth)

To avoid the heat in the west, Fairfield’s water park did the job.

In the NRL, the Eels played the Tigers at Parramatta in 37 degrees.

It wasn’t enough to hamper play, according to a heat stress tracker that considers a number of factors including temperature, humidity and wind.

The heat has prompted a total fire ban across greater Sydney, the central ranges, southern slopes and southern ranges regions.

Sydney heatwave Manly March 16
People flocked to Manly for a dip to escape the heat. (9News)
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