I would think even in the Summer in Canada it gets warm enough to make wax pretty sticky--especially in your pocket. Plus, it's harder to use wax to keep your lips from getting chapped.
That's the tricky part, you have to get the right mixture thus hardness, soft enough to easily fluff up with finger and hard enough to not messy.
Besides it's not really a problem unless you leave it in the car, air temp is typically below 35°C in summer.