How electric car range is affected by extreme weather

Electric vehicles (EVs) differ from gas-powered ones in lots of obvious ways, but one of the less obvious differences is how their driving range is affected by extreme temperatures.

All vehicles lose range in very hot or very cold weather—it takes more gasoline to run the air conditioner on high or heat up a cold car by allowing it to idle, after all—but thanks to circumstances of battery chemistry and engineering, EVs are especially affected.

That doesn't mean they can't be driven in adverse weather, just that EV owners should take a few precautions and plan ahead to avoid unexpected drops in driving range. We look at how much EVs are affected by external temperatures, why it happens, and what you can do about it.

A Chevy Bolt EV being tested on the dynamometer.

Measuring EV range in extreme weather

To find out how much of an impact extreme weather has on driving range, AAA, in partnership with the Automobile Club of Southern California’s Automotive Research Center, tested 5 electric vehicles, all with a minimum EPA-estimated driving range of 100 miles. Real-world driving conditions were simulated using a dynamometer, essentially a treadmill for cars, in a closed testing cell where ambient temperature could be closely controlled. To determine the effects on driving range, scenarios for cold and hot weather conditions—both when using climate control and not—were compared to those of driving with an outside temperature of 75°F.

The results

When climate control wasn't in use, the estimated driving range for EVs was moderately affected by hot and cold temperatures when compared to testing conducted at 75°F. By contrast, climate control use resulted in considerable reductions in driving range.

20°F

12% decrease
in driving range

20°F with heater

41% decrease
in driving range

95°F

4% decrease
in driving range

95°F with A/C

17% decrease
in driving range

These results mean that on average, for every 100 miles an EV can drive at 75°F with the air conditioning off, it can drive 83 miles at 95°F with the air conditioning on. At the other extreme, it can drive just 59 miles at 20°F with the heater running.

For example, an EV with a 240-mile range might be able to drive round-trip between Los Angeles and Palm Springs on a full battery in mild weather, but with the air conditioning engaged in a 95°F heatwave, its range would be reduced by about 40 miles and the driver would need to recharge at least once.

Gasoline-powered cars lose range, too¹

20°F with cold start

11% decrease
in driving range

20°F with warm start

6% decrease
in driving range

95°F with A/C

17% decrease
in driving range

Electric vehicles aren't uniquely unsuited to extreme temperatures. Testing by the Argonne National Laboratory has found that gasoline vehicles suffer range loss, too, though this phenomenon is more commonly described as "reduced fuel economy" or "reduced mileage."

When the weather is very cold, gas engines have to burn extra fuel to bring the engine up to operating temperature—this is known as a "cold start." Engine fluids are also less efficient when cold. When it's really hot, they have to burn extra gas to run the air conditioner. In fact, by percentage, gasoline vehicles suffer the same range penalty at 95°F with the air conditioning on as EVs do.

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An EV battery pack, with orange high-voltage cables.

Why EV range drops in extreme weather

Reason No. 1: Batteries don't like extreme temperatures

Like any car component, the high-capacity lithium-ion batteries in an EV have a temperature range that they work best within. As temperatures fall, diffusion, conductivity, and reaction rates inside the battery cells drop. This leads to increased voltage perturbation and heat generation, consuming energy that could've otherwise propelled the vehicle. At very low temperatures, extra energy may be needed to heat the battery to prevent damage.

Similarly, at elevated temperatures, a cooling system must run to keep the battery from overheating. This also uses extra energy and thus effectively reduces driving range. Aggressive driving results in more heat generation, increasing battery cooling demands.

Climate control dial on a center console

Reason No. 2: Climate control uses a lot of electricity

The 2 biggest decreases in EV driving range in AAA's testing came when climate control was turned on. As anyone who's ever paid a utility bill during a hot summer or cold winter knows, air conditioners and space heaters use a lot of electricity.

Using the heater at below-freezing temperatures produced by far the largest drop in range. With gas-powered vehicles, the engine produces heat as a byproduct of burning fuel, which can be used to heat the cabin. But EVs have to run a separate electric heater.

What you can do

Plan ahead: Check the weather forecast before you head out on a long-distance trip to see if you'll be traveling in very hot or cold weather. If so, plan for more frequent stops to charge, and map out the charging stations you'll be using and the distance between them.

Pre-heat or pre-cool before unplugging: Make time to warm up or cool down the inside of the vehicle while still connected to the charger. This lets the battery save its charge for driving.

Dial the climate control back a little: There's no avoiding using the heater or air conditioning in freezing or sweltering weather, but if you're trying to stretch out your driving range, use them modestly. Just like an indoor thermostat, it's more efficient to set the climate control to a comfortable temperature and dress appropriately than to run it on full blast.

Park in a garage, if possible: Leaving the vehicle indoors can help keep the cabin temperature stable between drives, instead of letting it fluctuate between the extremes of the weather outside.

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