In the CBD, 347 people have reported losing power in and around Martin Place, York St, Pitt St, Darling Harbour, King St, Market St, Clarence St, Sussex St and George St.
Ausgrid has said it doesn’t believe the blackouts are related to the heatwave.
Officials had warned the heat could put a strain on systems as people cranked on the air conditioning, with planned maintenance also sparking a warning.
The Post Office at Martin Place appeared to be closed amid the outage.
Further west and a small outage in Yagoona is affecting 51 residents.
Ausgrid has said power likely to be back by 5.30pm.
Temperatures have hit 28 degrees in the city and 39 in the west.
“Emergency crews are on site at multiple locations across the city,” Ausgrid said
“The cause of the outage is still being investigated although it’s not believed to be heat related.”
