New South Wales firefighters face worsening weather conditions today with hot, dry winds and temperatures above 30 degrees Celsius.

Crews have worked through the night back-burning to get a handle on several large blazes burning out of control, particularly in the Southern Highlands, the Hawkesbury and the Blue Mountains.

Since last Thursday, more than 200 homes have been lost and the Rural Fire Service says there is the potential for more property loss today.

Schools in the Blue Mountains have been closed and residents in nursing homes moved to facilities closer to the city.

People with no urgent need to be in fire-affected areas are being urged to stay away.

Follow our live blog for updates on the situation throughout the day.