As spring weather arrives, drivers in electric vehicles (EVs) may notice that their cars are going farther between charges. They aren’t imagining things — like all vehicles, EVs operate more efficiently in temperate weather. To help grid planners and regulators better account for these seasonal effects, RMI is releasing a set of new scenarios in our GridUp EV load forecasting tool to showcase how changes in temperature can affect EV charging demand throughout the year.
What factors affect EV efficiency?
A vehicle’s efficiency boils down to two main factors: the friction it needs to overcome to keep moving forward, and the energy it uses to keep the passenger comfortable through air conditioning or heating (often called auxiliary energy use).
Friction reduces vehicle efficiency in three main ways: air resistance, rolling resistance (tires on the road), and drivetrain losses. In the case of air resistance and drivetrain losses, EVs are often more efficient than internal combustion engines, thanks to design decisions that reduce resistance and far fewer moving parts.
All vehicles, including EVs, use more auxiliary energy when the ambient temperature is either colder or hotter than what is comfortable (such as 68°F/20°C). In these conditions drivers use climate control systems to heat or cool the cabin. This is energy intensive, especially on very hot or cold days. While some electric vehicles use heat pumps to improve climate control efficiency, warming a vehicle requires more energy when the ambient temperature drops regardless of the technology used.
EVs also have a third, smaller factor that can impact their charging speed. Low temperatures can affect battery performance for most common battery chemistries, so some vehicles are designed to heat the battery pack to keep it within an optimal temperature range. This impact is typically only noticeable during high-speed charging in very cold weather, when the vehicle needs to warm the battery more to receive the higher power of a fast charge.
Why does EV efficiency matter?
Vehicle efficiency dictates overall energy demand, regardless of the fuel source. The efficiency of the EV fleet — including variations due to temperature — has important implications for the electric grid: all else equal, a less efficient EV fleet will require building more charging and grid infrastructure to meet the greater demand. While there are tools to mitigate the impacts of EV charging on the grid, making good, data-driven investments relies on decision makers at utilities and regulatory agencies being able to anticipate the scale and location of EV charging demand. This led us to develop our EV load forecasting tool GridUp.
This latest update to GridUp, which incorporates EV efficiency variations throughout the year, helps stakeholders such as utility distribution system planners and public utility commission regulatory staff gain more confidence in their ability to make the prudent infrastructure investments needed to serve EV load.
Additionally, while EVs have zero tailpipe emissions, their efficiency still influences upstream power sector emissions. As three-quarters of US electricity still comes from nonrenewable sources, lower EV efficiency means burning additional fossil fuels and therefore greater carbon and local air pollutant emissions (although EVs still have a much smaller carbon footprint than gasoline vehicles).
In numbers: the seasonal temperature effects on EV charging energy demand
To demonstrate how seasonal temperature changes can affect the energy needed to charge EVs, let’s take a closer look at the results from the new, temperature-dependent GridUp scenarios for two cities with very different climates: Phoenix and Minneapolis. We modeled the energy use of millions of trips individually, incorporating trip speed and seasonal snapshots of ambient temperature based on hourly weather data to determine how changes in operating friction and climate control use impacted the amount of energy used by a vehicle.
May 15, 2026 By Rollins Baird, Nick Pesta, Ben Shapiro
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