A father and son have documented their lucky escape from a forest fire in Montana, capturing their drive to escape the growing flames on video.

Justin Bilton and his 70-year-old father were forced to evacuate from the Lake Macdonald area in the Glacier National Park in Montana, not far from the United States and Canada border, due to increasing fire danger.

"We hiked back to the car to get out where it was parked at the end of a dead end road," Mr Bilton said.

The Howe Ridge fire was started by a lightning strike on August 11 and burned more than 1,400 hectares of forest before being contained on August 17.

Mr Bilton said he saw the fire spread over thousands of acres in a matter of hours.

In the video he can be heard voicing his concern about whether the car will explode as they drive across embers and the flames surround the car.

At times during the video, the car is licked by flames skirting the side of the road as the blaze grows in intensity.

"Do I go?" he asks his father as the flames appear above the trees, who responds saying; "we are going to find out up here in a minute. I think we can drive through this".

"Dad this is insane," Mr Bilton says just before the pair encounter a burning tree across the road.

Mr Bilton shared the video on YouTube, writing that they had to drive out from a dead-end road.

"The [wildfire] was between us and the only way out," he wrote.

"After we reached the downed, burning tree seen at the end of the video, I had to reverse all the way back to the trailhead, where we were lucky to flag down a boat."

Mr Bilton and his father made it to a lake at the end of the trailhead where they found two employees of the national park who rescued them.

"They saved our lives," he said.