Yes, the weather is in charge. It hasn't been below zero yet this year, if i remember correctly, but i did shoot my rifle several times in below zero weather last year, in December. This week has warmed to the point where i probably should have tried shooting from the bench, but i was too lazy to make the switch, because it is turning cold this week end, and into next week. Am not positive, but i believe i have shot about 20 times so far in 2015, and it is the warm cab of the truck, and not having to set up a bench in the snow, that makes it possible.
Reloading is simple, and easy. The butt is on the floor close to the gas pedal, and the end of the barrel is right in front of me. It is easy to empty the vial down the barrel, and it is easy to index the sabot. The range rod is cut short, so it can be easily manipulated inside the truck. Bolt actions, because of their length are more difficult to load, but that too, is manageable. Every thing is done from the driver' seat, except when i need to leak.
When it is really really cold, the heater is run between shots, but most times that isn't necessary. When it is cold, it is simple to keep the barrel from overheating, by just laying the rifle on the window rest, and steering column.
To me, it seems like shooting like this is better practice for hunting, because one must hold the rifle on the target. The rest, doesn't hold the rifle in place, like a shooting rest and/or bags do on a bench. When hunting i always try to find some sort of rest when i am getting ready to take a shot, and even though holding a rifle on a tree branch, or a bipod, is a way better than shooting free hand, it is still more shaky than it would be if things were perfect.