Like you, I've read that batteries are at risk any time it drops below freezing. However, like @lex says it depends on how cold the batteries themselves get. If you have them, keep a couple extras in your pockets to keep them warm until you're ready to shoot. When it's cold, these new batteries can shut off and then need to be warmed up to turn back on. Someone on here about a month ago explained it real well, but my CRS (can't remember s___) won't let me remember who. I think it was mjs1973 or chunk.
I take my camera on my daily walks with temps as low as 15 degrees, and have had no problems. I'm out from 30 mins to 1 hour. A warning here...be careful with moisture when moving your camera from warm to cold and then warm again.
Ken