A Kiwi winemaker in the thick of the California wildfires says he's never seen anything like it.

Nick Goldschmidt has a winery in the Alexander Valley in Sonoma.

He says he has to "pick like crazy" over the next 24 hours to save his grapes, before the wildfires get any closer.

"I'm looking a whole hill side, probably about two miles long, it's on fire.

"I've got helicopters going over me and I can see three-quarters of it is probably white smoke and one-quarter brown smoke."

Mr Goldschmidt says he has experienced fires as a winemaker before, but nothing like this.

"There's also a 747, believe it or not, dropping fire retardant at tree level. I've never seen anything like it."

Meanwhile, a New Zealand winemaker says her son is being cared for by kind strangers in California, after he had to flee the wildfires.

About 22 wildfires are raging in the state at the moment, with only 10 percent of the flames contained.

Marlborough winemaker Erica Crawford says her 23-year-old son Rory has been in the thick of it, working in Napa Valley vineyards.

She says he's had to flee the fires, along with some Australian workers.

Ms Crawford says he's struggling with not knowing what is happening and not knowing the valley well.

"Where do they go next?

"People have been incredibly kind, whilst they're under pressure themselves to offer their homes and help for young Kiwis while they're in strife over there."

At least 29 people have been killed while hundreds remain missing.