There are no emergency warnings in place - but the Rural Fire Service warned that this could change very quickly throughout the day.

Four "watch and act" warnings are in place: for the State Mine fire in Lithgow, and fires at Mount Victoria, Springwood, and Wollondilly in the southern highlands.

What do the warning levels mean?

Emergency: The highest level of bush fire alert. People in these areas may be in danger and need to take action immediately. Any delay puts life at risk.

Watch and act: There is heightened threat level. Conditions are changing, and people in theses areas needs to start taking action to protect themselves.

Advice: A fire has started. There is no immediate danger. Stay up-to-date in case the situation changes.

What roads are closed?

Motorists are advised to avoid non-essential travel on the Great Western Highway between Penrith and Lithgow on Wednesday.

Bells Line of Road remains closed between Bilpin and Lithgow, and Darling Causeway remains closed between Bell and Mt Victoria.

Motorists should consider delaying their journey until otherwise advised.

For more information about road closures and traffic conditions, click here. 

How are rail services affected?

Trains are not operating between Bathurst, Lithgow and Mount Victoria due to infrastructure damage caused by bushfires over the last week.

Buses are replacing trains and will stop at Bathurst, Lithgow and Mount Victoria

Which schools are closed?

On Wednesday, all public, Catholic and Independent schools, as well as child-care centres and pre-schools, in the Blue Mountains local government area will be closed.

For a comprehensive list, click here.

How many homes have been destroyed?

The Rural Fire Service says 208 homes have been destroyed, the majority in the Blue Mountains. A further 122 have been damaged.

Forty other buildings have been destroyed, and 11 damaged.

What caused the fires?

The Springwood and Mount Victoria fires were started by powerlines during strong winds, the Rural Fire Service says.

Fire investigators are yet to determine the cause of the State Mine Fire, which started on defence land. They will examine whether it was ignited by explosives training.

What is the weather forecast?

Wind is the main concern for firefighters on Wednesday.

The Bureau of Meteorology is forecasting a top of 31 degrees in the lower Blue Mountains.

It will be a partly day with isolated showers contracting to the north and clearing by late morning.

There is a chance of late morning thunderstorms in the north.

Winds will be westerly 35 to 55 km/h, with gusts of between 80 and 100km/h. Humidity will be very low.

Fire ban

The RFS has issued a fire ban for the Central Ranges, New England, Northern Slopes, North Western, Illawarra/Shoalhaven, Greater Sydney Region, Greater Hunter, North Coast and Far North Coast districts.

All national parks are closed across the greater Sydney metropolitan area.

How can I donate?

The Salvation Army Bushfire Relief Appeal

salvos.org.au; 13 72 58

Red Cross Disaster Relief and Recovery

redcross.org.au; 1800 811 700

St Vincent de Paul Society NSW Bushfire Appeal

vinnies.org.au; 13 18 12

Woolworths stores are accepting donations for the Salvos and will match public donations dollar-for-dollar.

Coles stores in the ACT and NSW are accepting donations for the Red Cross.

Bushfire information line:

1800 679 737