New research from AAA finds that dramatic temperatures outside coupled with the use of an HVAC system to heat up or cool down the interior result in reduced driving range for electric vehicles.

Specifically, when the mercury drops to 20°F and the HVAC system is used to heat the inside of the vehicle, the average driving range is decreased by 41%. This means for every 100 miles of combined urban/highway driving, the range at 20°F would be reduced to 59 miles.

The study also found that when outside temperatures rose to a steamy 95°F and air-conditioning is used inside the vehicle, driving range decreases by 17%.

Noteworthy, when an HVAC system is not in use, the estimated driving range for electric vehicles was only moderately impacted by extreme temperatures. For example, when the HVAC system was turned off, an outside temperature of 20°F resulted in just a 12% decrease in driving range while an outside temperature of 95°F resulted in only a 4% decrease.

For drivers using electric vehicles in extreme climates, an unexpected drop in driving range can be a safety hazard leaving them stranded on the side of a road with a dead battery.

AAA recommends that drivers plan ahead by being aware of weather conditions before getting behind the wheel. During extreme temperatures, be prepared to charge more often, make time to “pre-heat” or cool down the inside while the vehicle is still connected to the charger as this reduces demand on the battery, and park in a garage to stabilize cabin temperature.