A convoy of 57 firefighters, chainsaw crews and forestry experts depart this week to help their counterparts fight wildfires in America's north-west.

It's senior firefighter Cameron Grylls' first deployment overseas.

"It's going to be pretty different for us given the scale and the size of what they're dealing with over there," Grylls said.

"It's just that next level so we're expecting some long hot days and a lot of strenuous exercise, but we're going to to help our teammates out over there and do our best."

He's Fire and Emergency's assistant district commander for Waikato and would be leading a crew of boots on the ground - they could be deployed to any of the neighbouring states of Oregon, Washington State or Idaho.

They would spend 28 days firefighting.

The team is made up of 43 personnel from Fire and Emergency, four from the Department of Conservation (DOC), five from the Defence Force and five from the forestry industry.

They would be taking on multiple roles, ranging from firefighters and fire engine crews to chainsaw specialists, and including incident management roles such as helibase managers, logistics and liaison officers.

"They could be blacking out, that's extinguishing, dampening down where fires have gone through so that they don't reignite, could be clearing access for other crews, cutting down trees," Grylls said.

"We go over with a fairly open mind and know that we're going over to help them in whatever task they might need doing. So we're pretty flexible."

In western Canada, over 20,000 people were forced to flee communities in British Columbia over the weekend and in the US, crews in Washington have been fighting three wildfires that began burning in the Spokane area.

The New Zealand firefighters are experienced working in arduous conditions, including steep terrain and high temperatures, and living in fire camps in remote areas.

It's not just the scale of the wildfires that would be challenging for the Kiwi crews - they've been told to keep an eye out for local wildlife.

"Bears, scorpions, rattlesnakes any of those sorts of things that we typically don't have over here that are out to hurt us. It's a different environment for us...we just have to keep our wits about us."

Blair Calder is a DOC ranger in Dunedin and his team is likely to be focused on making fire breaks.

"There'll be a lot of walking onto the fire ground then there'll be a lot of using hand tools and not a lot of water, possibly, where we're going. We've got chainsaw operators with us," Calder said.

"It's crucial and it can be very time consuming and physically demanding."

This was his sixth deployment overseas, he'd been to Canada and Australia to join firefighting efforts.

"I really enjoy the challenge. I enjoy working with other people from around New Zealand who you don't always get to work with.

"When you get over there, the upskilling you get from 28 days of firefighting is pretty intense and it's a really good way to learn."

Forestry-trained firefighters have worked with Fire and Emergency in overseas deployments for decades, bringing specialised chainsaw skills and expertise.

Forestry worker Jarron McInnes is going to the US as a leader for a chainsaw crew and had previously fought wildfires in Canada and Australia.

"It's their chainsaw skills where they really shine - tree felling, cutting fire breaks and fire lines," he said.

Defence force Staff Sergeant Matthew Anker is a Fire Master based in Waiouru and he said it was the type of deployment soldiers train for.

"They are experienced in wildfire response and accustomed to operating in demanding environments as part of a coordinated multi-agency team," he said.

"It is an opportunity for them to apply those skills in support of our international partners, while gaining further experience that will strengthen our response capability at home."

Cameron Grylls said they would come back home to New Zealand with news skills to tackle an expected dry spring and summer...something crews were already preparing for.

"Some brigades are looking at going out and starting up training around working with helicopters and all of that rural aspect that we do...our crews are very much aware of that and looking to start building that into their training now as we move forward into that season."

Some of the fire fighters departed for the US on Tuesday and the remainder leave Wednesday.

Two other deployments are already on the ground in the US and Canada, with five working on fires in Washington State and Oregon and six in British Columbia.