It happens to me at about minus 5 degrees Fahrenheit. The pawls inside the freehub on my bike don't catch, or don't catch reliably. Hence the freehub just spins and spins and I can't pedal.
So far, I've been able to make due by pounding the wheel on the ground to loosen the pawls and spinning the cranks fast to generate a bit of friction heat. Then they catch and I can proceed, but the same thing can just happen again at the next stoplight. What I need to do is overhaul the freehub with a low temperature grease. I just haven't gotten around to it yet. Fortunately we only hit minus 5 F here once or twice a winter.