I've run 650CCA batteries during the winter in my diesel with no problems. If there is nothing wrong with your battery don't worry about it but if you are buying a new one get one with the highest CCAs that you can afford
I had a 10 year old VW dealer 650 CCA battery and the car was not plugged in at -40 and it started. I had to try 3 times before it started and stayed running. It had been sitting outside since it last ran for about 6 hours
Cold cranking amps (CCA) is the amount of current a battery can provide at 0°F (−18°C). The rating is defined as the amperage a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). It is a more demanding test than those at higher temperatures.