Sydney's late-summer spell of unusual warmth shows little sign of making way for autumn with another week of mild to hot weather ahead.

The city has notched a record run of 25 days of above 26 degrees in a row, including Monday. On current forecasts, that tally could stretch to 33 days or more, said Rob Sharpe, a meteorologist with Weatherzone. The previous longest streak was 19 in 2014.

Monday may be one of the coolest of the days of the coming week, with the forecast top of 27 degrees exceeded and a few showers tipped. February's long-run average is 25.8 degrees.

The mercury from Wednesday is expected to reach 30 degrees in Sydney for six consecutive days. If reached, it would be a new late-season heat burst for the city with the only run of such heat landing just once - in January-February 2011.