Extreme cold conditions can have an effect on lubricated and mechanical components, you have a cable that runs from the front of the vehicle to the rear brakes. If it is frozen then yes, you may have to play the wait game.
It could be that the cables are frozen, but for this to happen they would have had to have been exposed to snow or water. This can also happen if you park in deep snow.
If this is not the case, it is also possible that there is an issue with your brake pads or shoes. One thing you can try is to back the vehicle up slowly just a little bit and see if you can release the brake lever after that. Be very careful not to drive too much, as the vehicle is not meant to be driven with the brake on. If you feel any resistance do not drive further. At this point you may need to have the vehicle towed in to find the problem.
〉 Answered on Jan 18th, 2009 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines