A COOL southerly change is expected through Sydney this morning, bringing desperately needed relief to firefighters.

Temperatures are expected to drop and there is the good possibility of showers in the afternoon.

Rain is also being forecast for tomorrow.

The Bureau of Meteorology is forecasting the cooler southerly change to pass through Sydney about 10am, with conditions beginning to warm up again by Wednesday.

There is a wind warning out for NSW coastal waters, and it is feared there will be warm to very warm winds before the southerly change — conditions that could cause the fires to flare up early in the morning.

William Baini from the consultancy firm Weatherwatch said the cooler weather expected over the next couple of days represented a return to more normal conditions.

“The outlook is definitely more positive,” Mr Baini said. “There’s a cold front coming through from the south, which is bringing colder air and moisture off the southern Pacific Ocean. This is a more normal pattern than the intense heat we’ve been experiencing.”