I did a weekend golfing get-a-way in the Adirondacks this past weekend. I took my P4 with me and left it in my vehicle, temps in the morning were in the 40's. On the last morning there, I decided to take flight and get some pics of the area. I wasn't able to launch because of a cold battery, so I jumped in my vehicle, turned on the heat and warmed up the battery for about 5 minutes and that's all it took. Just another way to do your own troubleshooting!   

I'm sure you got just as much benefit being in that warm car as the battery.

I've seen some users placing their batteries in their pockets when going from the car to the launch site when you know it's going to be a bit of a trek.

Often wondered about the batteries when I see the Canadian snow shots. Does the intense cold shut the battery down?

I found out about the battery vs cold issue the same ways. I keep batteries in my coat now. I never run them down below 25% to be safe in cold.
Here's an example:

well that'll freeze the cells off your battery. Nice to watch.