Police say the woman was last seen berry picking with her family in an isolated forest near Mont St-Michel, about 30 kilometres of Mont Laurier.
"She told the person that was with [her] that she was going back to the cottage. The people …went back to the cottage. She wasn't there," said Sûreté du Québec spokesman Sgt. Marc Tessier.
Police said the woman was reported missing at around 2 p.m. Sunday.
Rescue teams are searching for the woman using a helicopter, all-terrain vehicles and a police canine unit.
Tessier said officers worked through the night, but the search was complicated by a thunderstorm early this morning.
Police are asking for help from volunteers who have experience searching in heavily-wooded areas.