UPDATED 11.51AM: With gale force winds forecast this afternoon Marlborough firefighters face a daunting challenge trying to stop a large forestry blaze from spreading.

Nine helicopters using monsoon buckets are working with 70 ground crew to contain the blaze, which has torn through 450 hectares of the Waikakaho Valley.

Strong winds are already fanning the flames through ridges and gullies, and they're expected to reach gale force this afternoon.

Principal Rural Fire Officer Richard McNamara said they're throwing everything they have at it quickly, before the wind restricts flying.

At this stage homes in the area are safe, but people have been evacuated and several vehicles have been destroyed by the fire.

Principal rural fire officer Richard McNamara says they're doing all they can to build up containment lines.

"[The houses are] not under direct threat at the moment but of course the big factor here is increasing temperature and increasing wind, [it's] very volatile, very erratic fire behaviour that occurs as a result of increases of win in that complicated gully system."

Operations Manager for Marlborough Lines Brian Tapp says they're doing the best they can to restore power to 25 lifestyle and farming properties. They are using a helicopter to "make sure there's been no damage to the power lines because of the fire."