Canada’s Cannabis Act will come into effect on October 17, 2018.
Illegal to cross Canadian borders
But it’s important to remember that, even after that date, it will remain illegal to travel across the border and internationally with cannabis (marijuana) in your possession. The Canadian Border and Services Agency recommends that you don’t bring it in, don’t take it out.
Flights within Canada - Possible Diversions
In the case of a domestic flight, please be advised that unforeseen situations may and do arise that require a domestic flight to divert to a U.S. airport, where arriving in possession of cannabis is not legal.
If you are refused entry into a country because you have cannabis in your possession, you alone will be responsible for the consequences, including for payment of your return trip home.
The following Government of Canada links offer useful information on cannabis and travel: