Temperatures will reach the mid-thirties across the Sydney Basin on Friday, with the city forecast to have one of its warmest days on record for this late in autumn.

A pulse of hot northwesterly winds flow through the Sydney Basin on Friday ahead of an approaching cold front.

Image: Surface temperature at 4pm AEDT on Friday according to the ACCESS-C model.

The fresh offshore winds are likely to cause fairly uniform heat across Sydney's suburbs, with temperatures forecast to reach 36-37 degrees from Penrith to Bondi in the afternoon.

If Sydney's Observatory Hill weather station reaches 35.5 degrees, it will be the city's hottest day this late in autumn since 1998. If it gets to 35.7 degrees, it will be the hottest day this late in the season since 1940.

In records dating back to 1859, Sydney has only registered five autumn days over 36 degrees on or after March 20th, the highest being 38.7 degrees on March 28th, 1940.