Dozens of kiwi firefighters are preparing to jet over to California to help combat wildfires raging out of control.

They're expected to fly over as early as next week.

Fire and Emergency National Manager Kevin O'Connor says they'll be relieving firefighters who have been battling the massive blaze for more than a week.

"They are in extreme conditions. Their firefighters and very fatigued and tired, and hence they have requested Australia and New Zealand and Mexico to give them some support."

O'Connor says the US is covering their expenses, and paying a daily rate to each firefighter working in the risky conditions.

"We're not there to make money out of it, but it does cover our costs. From our point of view, it is a great training and development opportunity as well so we get a lot out of it as well."

LISTEN TO KEVIN O'CONNOR TALK WITH LARRY WILLIAMS ABOVE