Also low 30's (assuming F) is not "battery cold", it's just mildly chilly and most sleeping bags would handle that temperature easily. I've camped before in sub-zero (again F) temperatures before and that's not at all uncomfortable with the right equipment.
It must be F. I wouldn't want to be sleeping in a tent if if were low 30's in C as I'd be too busy sweating to get any sleep at all. For example here in Finland the official heat threshold is 25 C and warmer countries have the limit a few degrees higher. 30 whatever is still really warm in C. Seems like low 30's in F are around 0 C and decent camping gear should have no problem with that like you mentioned.