Lower Hunter Rural Fire Service public liaison officer Terry Burns said four crews were on scene at Greta, keeping an eye on a few internal hot spots.

Mr Burns said the North Rothbury fire is "well and truly out" but crews are still patrolling the site.

Both fires reached emergency level on Tuesday afternoon before being downgraded later in the day. The Greta blaze flared up to Watch and Act after the fire broke containment lines on Wednesday.

But Mr Burns said it is now fully contained.

Fire investigators were on the scene of both incidents on Wednesday trying to discover if the fires were deliberately lit. They are currently being treated as suspicious.

Mr Burns said RFS building impact analysis teams would attend the scenes today to determine the full extent of the damage.

The conditions are better today than earlier in the week, Mr Burns said, with no total fire bans in place. But the fire danger rating remains "very high".