WestJet Flight 150, destined for Edmonton, was carrying 134 passengers and six crew members as it pulled away from the terminal shortly before 8 a.m. on Monday, said airline spokesman Robert Palmer.
The plane was moving at about 15 kilometres per hour when at least some of its wheels left the tarmac. There were no injuries.
A storm was blanketing the area with heavy snow at the time, causing poor visibility, but Palmer said the exact cause was still under investigation.
"It appears to be weather related at this time — they're having quite the snowstorm there and it's difficult to see where the tarmac stops and the grass starts because it's under a whole bunch of snow," Palmer said.
"It would be similar to your car, if you were making a turn and as you made the turn you slid sideways a little bit and ended up catching a bunch of snow."
Palmer said the nose wheels and the wheels below the right wing were off the pavement and in the snow-covered grass.
All the passengers were OK and were being rebooked on other flights, Palmer said.
However, the snowstorm had cancelled other flights into and out of Kelowna and it wasn't clear when all of the passengers would make it to Edmonton. WestJet planned to pay for their meals, accommodation and travel until they were able to depart, Palmer said.
He said crews were inspecting the plane for damage before determining if it could return to service but that the slow speed meant it's unlikely the aircraft sustained any serious damage.