Two bushfires are out of control near Bega in the southeast of NSW as the entire state experiences hot and windy conditions.

The NSW Rural Fire Service on Sunday afternoon issued watch and act alerts for the fires at Bega and another near Goulburn, northeast of Canberra.

A fire at Kerrisons Lane and Northview Close at Bega "is burning close to isolated properties", the service said, adding "if the fire reaches your property, protect yourself from the heat of the fire".

The advice continued: "If you plan to leave, or you are not prepared, leave early."

A similar alert was issued for a bushfire at Tarraganda, southeast of Bega, near Reedy Swamp Road.

Elsewhere another watch and act alert was issued for a fire at Tarlo River Road in Greenwich Park northeast of Goulburn.

"Firefighters are on scene. Additional crews are being sent to assist," the RFS said.

Total fire bans were issued for more than half of NSW on Sunday including the Greater Sydney region given the hot and windy conditions. Twelve of the state's 21 regions are experiencing severe fire conditions.

Temperatures soared to 38C at 3pm in Sydney's CBD while further west at Penrith they reached 38.2C.

In Bega the mercury hit 38.4C at 3pm while at Goulburn it was slightly cooler at 33C.