How does temperature affect my batteries?
The capacity and life expectancy of a lead acid battery will vary depending on the temperatures that it operates in. Battery capacity increases in hotter temperatures though battery life decreases. Also in the colder temperatures the battery will have less capacity but it will last longer. At freezing battery capacity is about 20% lower, at 122 degrees F battery capacity is around 12% higher.
The charging voltage for a battery will also vary from 2.74 volts per cell (16.4 for a 12v battery) at -40c to 2.3 volts per cell (13.8 on a 12 volt battery) at 50c. Some charge controllers have this temperature correction built in.