Canada is one of the few places on earth where an EV owner might see a -30°C cold snap in January and a 40°C heat dome in July, in the same vehicle, in the same year. We've covered both extremes individually — our winter range loss data and our heat wave range loss data — but the head-to-head question comes up constantly: which one is actually worse?

Based on real 2026 data, the answer is clear on range, and more nuanced on long-term battery health.

Round 1: Range loss

A 2026 AAA study found EVs lose approximately 39% of driving range at 20°F (-6.7°C), with efficiency declining by 35.6% under the same conditions. That's a severe hit, and it's worth noting -6.7°C isn't even an extreme Canadian cold snap — it's a fairly ordinary winter day in most of the country. Real Canadian cold snaps regularly dip to -20°C or -30°C, conditions colder than AAA's test point, where range loss climbs further.

Compare that to heat: real-world fleet data shows range loss staying modest — around 5% — up to 90°F (32°C), only climbing sharply past 95°F (35°C), reaching as much as 31% at 100°F (38°C) in some datasets.

Winner: cold, clearly. Not only does cold cause a larger maximum range loss in the data we have, it does so at a less extreme temperature. -6.7°C is a mild winter evening; 38°C is a genuine, headline-making heat dome. Cold is the more consistent, more frequent range threat across an average Canadian year.

Round 2: Operating cost

AAA's cold-weather study also quantified the cost side, which rarely gets discussed alongside range: winter conditions added $32.11 per 1,000 miles in extra cost for home charging, and a steeper $76.93 per 1,000 miles for owners relying on public charging — a direct consequence of needing more energy to cover the same distance. We don't have an equivalent heat-specific cost dataset, but given the smaller range loss involved, it's reasonable to expect the cost impact of heat is proportionally smaller too, at least below the 35°C threshold where things get more severe.

Winner: cold, again, on the data available.

Round 3: Long-term battery health

This is where the story flips. Cold weather's range loss is almost entirely temporary — a battery that's cold performs worse in the moment (reduced chemical reaction rate, energy spent on cabin heating) but isn't permanently damaged by a single cold snap or even a full Canadian winter, provided it isn't charged at extremely low temperatures without preconditioning.

Heat is different. A 2026 study in Scientific Reports examining lithium-ion battery modules found batteries become measurably sensitive to permanent degradation once sustained temperatures exceed roughly 35°C, with some cells dropping below the 80% State of Health threshold generally considered end-of-useful-life under prolonged high-heat exposure. Our heat and battery degradation piece covers this in more depth — the short version is that heat's damage can outlast the heat wave itself, in a way cold's damage generally doesn't.

Winner: heat, for long-term battery health specifically, even though it loses on immediate range impact.

So which one should you actually worry about?

Both, but for different reasons and on different timelines:

  • Cold is the bigger day-to-day, season-to-season range and cost concern for the average Canadian EV owner — it happens every winter, affects a larger share of the country, and the range loss is more severe at more moderate temperatures than heat's equivalent.

  • Heat is the bigger long-term, cumulative battery health concern, specifically for owners in regions that see repeated 35°C+ stretches — the Okanagan, southern Prairies, and increasingly other parts of the country during heat domes. This matters most for used-EV buyers evaluating a vehicle's climate history, not just its current range.

What this means for a used EV buyer

If you're buying used and comparing two similar vehicles from different regions, weight cold-weather history a bit more heavily for immediate driving experience and cost, and weight heat exposure history a bit more heavily for long-term battery capacity. Either way, the single most useful check remains the same: a direct battery State of Health reading, which reflects the cumulative effect of whatever climate extremes the vehicle has actually seen, rather than relying on general assumptions about where it came from.

The bottom line

Cold wins on immediate range loss and operating cost — it causes a bigger hit at a milder temperature, and it happens every year across nearly all of Canada. Heat wins on long-term, permanent battery degradation risk once sustained temperatures cross roughly 35°C. Neither is a reason to avoid a used EV; both are reasons to check battery health directly rather than assuming a car's history doesn't matter.

FAQ

Is cold or heat worse for an EV's range right now, in the moment? Cold, clearly. A 2026 AAA study found roughly 39% range loss at just -6.7°C, compared to roughly 5% range loss at a similar-magnitude heat exposure (32°C), with heat only becoming comparably severe above 35°C.

Is cold or heat worse for an EV battery's long-term health? Heat. Cold-related range loss is largely temporary, while sustained heat above roughly 35°C has been shown in recent research to cause permanent capacity loss.

Which matters more for buying a used EV? Both, depending on what you're evaluating — cold-weather history relates more to day-to-day range and cost, while heat exposure history relates more to long-term battery capacity. A direct State of Health check captures the cumulative effect of both.

Sources: AAA Newsroom, "AAA Study Reveals Temperature Impacts on EV and Hybrid Performance, Efficiency and Costs" (2026); Nature Scientific Reports, lithium-ion thermal degradation study (2026).