Cool change due for southern NSW

Conditions across the southern half of NSW are expected to ease over the weekend but the mercury will likely remain in the low to mid 40s in the state's north.

After copping temperatures up to 45C on Friday, Sydney's west is forecast for a milder maximum of 35C on Saturday while in the coastal parts of the city it is due to reach 31C.

But for those in the far north it is expected to remain hot with a predicted high of 41C at Grafton.

The cool change will probably remain for Sunday with the Bureau of Meteorology expecting temperatures to lower towards averages in the mid 20s to low 30s.

By Tuesday the heat is forecast to return to much of the state with maximums creeping back up into the low 40s.