Electric Vehicles (EVs) offer a large number of benefits to users. They are highly energy-efficient and work wonders in reducing carbon footprint, especially when the power comes from clean utility companies or solar power from home or the workplace.

These environmentally friendly modes of transportation also serve to reduce fuel costs for drivers. While driving a car that runs of traditional fuel, drivers are used to constantly checking the fuel gauge to ensure that they have enough fuel to reach their desired location without any bumps.
Similarly, EV drivers are known to have range anxiety. Range anxiety is the constant fear that you might end up stranded in the middle of nowhere because your EV just ran out of juice midway. Of course, this eventuality is not something you have to worry about on a daily basis.

However, it is important to know where the closest charging stations are and what factors affect the range of your electric vehicle. As per a 2014 report released by the AAA (American Automobile Association) Automotive Research Center based in Southern California, extreme external temperatures may have a significant effect on the range of your EV.

Study Results
The AAA study was conducted by running tests on a 2014 Ford Focus, 2013 Nissan Leaf, and a 212 Mitsubishi i-MiEV. In a climate-controlled room, these cars were run from full capacity to a completely depleted battery using a city-traffic driving format. The results clearly show that extreme weather and external temperatures affect the range of an electric car detrimentally.
Control figures: EV battery range was ideal when the temperature was recorded at a regular 75° Fahrenheit. On an average, the cars displayed an average range of 105 miles.

Extreme cold weather: In extreme cold weather temperatures of 20° F, it was observed that the EV battery range dropped by a stunning 57%. The combined average range recorded was just 43 miles.

Extreme hot weather: In extreme hot weather temperatures of 95° F, it was observed that the EV battery range dropped by 33%. The combined average range recorded was 69 miles for a fully charged EV.

The Answer
The primary reason why extreme hot or cold weather affects the range of electric cars is that the cars have to work much harder to produce the equivalent amount of electricity as it would have required in regular temperatures. There are ways to combat this situation. EVs like the Nissan Leaf, Tesla Roadster, and Coda Sedan come with active thermal management systems which work to minimize the effects of extreme external temperatures. By keeping the battery cooled or heated enough for it to run at its optimum operating temperature irrespective of the external temperature, these systems work efficiently.

Other variables that affect the effect of external temperatures on EV range are battery types, existence of thermal management systems, and how the car is being driven. There is plenty of debate about whether air or liquid systems should be used to maintain optimum operating temperatures but the active thermal management systems are the best available options right now.