Martin and Karen Waterman have lived on the NSW Central Coast for more than 20 years, but they've never experienced anything like the "megafire" bearing down on their property as emergency blazes rage across the state.
A huge 250,000-hectare bushfire at Gospers Mountain northwest of Sydney has joined up with the neighbouring Little L Complex and Paddock Run blazes.
Emergency warnings were also current on Friday evening for the nearby Wrights Creek blaze west of Kulnara, the Kerry Ridge fire in the Wollemi National Park and the Meads Creek West fire in the Goulburn River National Park.
The Watermans run the Karingal Equestrian Centre at Mangrove Mountain where they live with 22 horses.
Ms Waterman on Friday could see just 30 metres in front of the house.
The couple has been preparing to defend the property - and their horses - since the Gospers Mountain fire kicked off in mid-November. Mr Waterman has also been fighting nearby fires as a NSW Rural Fire Service volunteer.
"We've been enacting fire plans for weeks in preparation," Ms Waterman told AAP.
"It's about putting in the time and effort into trying to make your place as saveable as possible."
Should the fire threaten them directly they'll "definitely" stay and defend the property, she said.
The couple has lived through a number of fires previously but this one is "different to anything that has been up here", Ms Waterman said.
"The resources are so stretched because of the huge number of fires up and down the coast. Then on top of that, there are unprecedented dry conditions. We haven't had these circumstances ever that I know of."
Hawkesbury City Council deputy mayor Mary Lyons-Buckett can see the Gospers Mountain fire from her home in Kurrajong.
"There's smoke along the ridgeline - it has quite an orange glow to it," Ms Lyons-Buckett told AAP.
Driving home the horizon looked "almost like a painting with lots of different hues of orange and grey and then there was another big pall of smoke that was whiter", she said on Friday.
"The thing that is nerve-wracking for people is that so much depends on the way the wind comes and where the fire is going to go.
"Locals are quite astonished by the size of this fire - it is a megafire."
The deputy mayor said while the community was resilient and strong "this fire is something that is testing many people".
RFS deputy commissioner Rob Rogers on Friday said time would tell how far east the megafire pushed.
"We're quite concerned about the potential of this fire, we've got a lot of trucks in the area trying to stop it and we've got aircraft trying to slow it down," he told ABC TV.
"But on days like today we just cannot stop these fires, they'll just keep burning until conditions ease and then we'll try and do what we can to contain them."
The RFS on Friday evening said fire activity was increasing in the Lower Portland and Central Colo areas.
"There is a risk to life and properties in this area," the service warned. "Seek shelter as the fire front approaches."
Residents in the area of Kulnara have also been told "you are at risk".