AN "out-of-control" bushfire is threatening homes in far south NSW with residents near Ulladulla being told it is too late to leave.

Two other blazes have been reported, one west of Kiama and the other at North Nowra with homes said to be under threat along the Princes Highway.

The triple fire threat prompted the NSW Rural Fire Service to make the "extremely rare" decision to declare a total fire ban for Sydney in winter.

The Ulladulla firefront has burnt through about 100 hectares and properties west of Burrill Lake are currently under threat.

An emergency warning - the highest possible alert - has been issued by the RFS but some residents have been told it is too dangerous to leave.

ROLLING COVERAGE: SOUTH COAST BUSHFIRES

No properties have yet been lost but strong winds and incredibly dry conditions are exacerbating the situation and hampering fire crews.

"Residents in the area of Kingspoint and areas west of Burrill Lake and Ulladulla are advised to seek shelter in a solid structure as the fire impacts," the RFS said this morning.

The fire - about 100 hectares in size - is being fanned by very strong north- westerly winds, with gusts of up to 60km/h.

"Under these conditions, fires are uncontrollable, unpredictable and fast- moving." A grass fire was also burning out of control in Jerrara, west of Kiama. The RFS said the fire was burning "close to properties" but crews were on scene to try protect them.

Fire crews had already been on high alert with warm and windy weather forecast across the state.

The RFS has urged property owners to think twice before burning off on Wednesday, as temperatures rise to the mid-20s amid winds of up to 70km/h. Firefighters were kept busy last weekend with "irresponsible" and "careless" landholders behind dozens of escaped and illegal burns in windy conditions, some of which threatened homes.

Some 48 incidents were reported across the state between Friday and Sunday, 10 more than the previous weekend.

Commissioner Shane Fitzsimmons said the activity was extremely concerning. "Escaped fires pose a very real and potentially deadly threat to the public, especially if that escaped burn takes hold and fire authorities are not notified," he said.

Landholders who fail to notify authorities and neighbours face fines of up to $5500 and/or 12 months in jail, while escaped fires can attract penalties of up to $110,000 and/or five years' prison.

The bushfire danger period has already begun in parts of the state, including Lismore, Richmond Valley, Armidale and Walcha.

It will start in other local government areas, such as Coffs Harbour and Kempsey, from Friday.

WHAT DOES A TOTAL FIRE BAN MEAN:

● On a day of a total fire ban, you can use a gas or electric barbecue outside, as long as an adult supervises it. There is no flammable material within five metres.

● All barbecues which use solid fuel such as wood, charcoal or briquettes are banned.

● A barbecue or wood fire pizza oven which uses solid fuel, such as wood, charcoal or heat beads, cannot be used outside during a Total Fire Ban.

● Permits are suspended on days of total fire ban. Permits may resume after the total fire ban is lifted, as long as the permit hasn't expired.