COOLER conditions have broken Sydney's heatwave but about 80 fires are still burning across NSW.

Today a top temperature of 21C is forecast for Sydney city - down from 40.4C yesterday.

No total fire bans are in place for today, while a "very high'' fire rating applies for most of central and western NSW.

The cooler conditions are especially welcome in the state's central west, where a fire burning west of the townships of Kandos and Rylstone was especially worrying for firefighters yesterday.

A threat to properties at the towns has now eased, with residents who voluntarily left their homes on the weekend being advised they could return late yesterday evening.

"The pinnacle fire did breach its containment lines and impacted on properties on the north west of the township of Rylestone,'' NSW Rural Fire Commissioner Shane Fitzsimmons told ABC radio today.

"That fire, while we have some welcome relief, is certainly not contained yet,'' he said.

One property, a cottage at Rylestone, was destroyed in the blaze, while a dozen cattle were lost to a fast running grass fire at Orange.

While the cooler conditions were welcome, Mr Fitzsimmons said there were "days and days'' of work left for firefighters to do.

"A lot of dirty, tough, arduous work to lock in these consolidation lines and to be able to declare these fires contained before we return to warmer weather on Thursday and Friday,'' he said.