The NSW government will declare a third state of emergency of the bushfire season ahead of re-elevated fire risk over the weekend.

Premier Gladys Berejiklian said the declaration would come into effect from Friday morning, with severe to extreme conditions forecast for Saturday.

In the video above: The latest on NSW bushfires

"All our personnel, all our agencies know that from tomorrow they will be subject to forced evacuations, road closures, road openings and anything else we need to do as a state to keep our residents and to keep property safe," ," Ms Berejiklian told reporters on Thursday.

"We don't take these decisions lightly.

"But we also want to make sure we're taking every single precaution to be prepared for what could be a horrible day on Saturday."

More than 100 fires are burning across NSW, with over half uncontained. Credit: AAP

What does it mean?

The state of emergency declaration falls under Section 33 of the State of Emergency and Rescue Management Act 1989 and was made on Thursday in anticipation of intense heat and extreme fire danger conditions across NSW.

It allows powers to be transferred from the NSW government to the Rural Fire Service commissioner.

The declaration is valid for a period of seven days from Thursday.

What are the powers?

Direct any NSW government agency to conduct or refrain from conducting its functions

Control and coordinate the allocation of government resources

Evacuate people from property within the declared area

Play Video NSW firefighter killed in the line of duty remembered. NSW firefighter killed in the line of duty remembered.

Close roads and thoroughfares to traffic

Pull down or shore up infrastructure at risk of collapse

Order the shutdown of essential utilities in the declared area, including electricity, gas, oil and water

Enter or take possession of property in the course of the emergency response.

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