How much hotter than the outside air does a closed car get?
Roughly 20 °C or more within an hour on a sunny day, and most of it arrives in the first half hour. Two sources put numbers on it.
A 2005 study in Pediatrics by McLaren, Null and Quinn logged the cabin of a dark sedan for 60 minutes on 16 clear, sunny days, with outside air between 22 °C and 36 °C. The interior rose by an average of about 1.8 °C every five minutes, about 80% of the rise came in the first 30 minutes, and the average gain over the hour was roughly 22 °C. On the coolest test day, 22 °C outside, the cabin still reached 47 °C.
| Source | Outside air | Inside the car |
|---|---|---|
| McLaren et al., coolest test day | 22 °C | 47 °C after an hour |
| McLaren et al., average across 16 days | 22–36 °C | About 22 °C above outside after an hour |
| BC government heat bulletin, June 2021 | 34 °C | Up to 52 °C within 20 minutes |
The study reported its results in Fahrenheit; the figures here are converted to Celsius.
How hot does Langley get in summer?
Hot enough to push a parked car past 45 °C on an ordinary sunny afternoon. Abbotsford Airport, the long-record station about 20 km up the valley, averages highs of 24.0 °C in July and 24.4 °C in August, and 8.7 days a year over 30 °C, in ECCC’s 1981–2010 climate normals.
Langley’s own station, Langley Regional at the airport, has daily records for the last three summers:
| Langley Regional station | 2024 | 2025 | 2026 |
|---|---|---|---|
| Hottest day | 32.7 °C (July 9) | 33.5 °C (August 11) | 33.9 °C (July 22) |
| Days at 30 °C or more | 6 | 11 | 8 |
The extreme sits much higher. At the peak of the 2021 heat wave, the thermometer at ECCC’s Fort Langley Telegraph Trail station reached 41.5 °C (June 28).
What do those numbers mean inside a car parked in Langley?
Put the study’s average rise on top of Langley weather and you get these rough figures. They’re arithmetic from published results, not readings taken in Langley.
| Langley day | Outside | Cabin air after about an hour in sun |
|---|---|---|
| Average July or August afternoon | About 24 °C | About 46 °C |
| Hottest day of 2026 | 33.9 °C | About 56 °C; the BC bulletin gives 52 °C within 20 minutes at 34 °C |
The second row matters most: July 22, 2026 was almost exactly the 34 °C day in the province’s warning, so that warning describes a real Langley afternoon.
Which parts of a parked car get the hottest?
The dashboard, then the steering wheel and seats. In a 2018 study by Vanos and colleagues in Tempe, Arizona, silver sedans, silver economy cars and white minivans sat for about an hour in full sun or full shade on days between 32.8 °C and 41.5 °C:
| Average reading | In the sun | In the shade |
|---|---|---|
| Cabin air (steady state) | 47.6 °C | 39.5 °C |
| Dashboard surface | 68.9 °C | 47.8 °C |
| Steering wheel | 53.3 °C | 41.7 °C |
| Seat | 50.6 °C | 41.1 °C |
Two things stand out for Langley drivers. Shade cut the dashboard reading by about 21 °C, more than any other change in the table. And the top of Arizona’s test range, 41.5 °C, is the same figure Fort Langley recorded in June 2021.
Do cracked windows or window tint keep a parked car cooler?
Cracked windows don’t, in any useful way. McLaren’s team opened the windows about 4 cm on two of their test days, and neither the rate of heating nor the peak temperature dropped meaningfully. BC’s bulletin says the same: slightly open windows will not keep the inside at a safe temperature.
Window film cuts the solar energy coming through the glass it covers. On LLumar’s performance data sheet, the share of the sun’s total energy kept out is 50–62% for IRX ceramic and 28–44% for ATC dyed film, measured on clear 6 mm glass. That lowers the heat load, but it has limits in BC:
- Under MVAR s. 7.05(8), legal film is limited to the glass behind the driver plus a 75 mm band at the top of the windshield. Everything forward of that, front door glass and most of the windshield, stays clear, so sun still lands on the dash.
- The shop does fit front-door or windshield film on request, and it explains the risk first: a car carrying that film can’t legally be driven in BC, Mission RCMP gives $109 as the usual ticket, and an officer can require the film removed and an inspection passed. More on that in the front window rule.
- Nobody has published a tinted-versus-untinted cabin measurement for Langley that we could find, so the shop quotes energy rejection, not degrees.
How film handles heat in more detail is on does ceramic tint really block heat.
Is it ever safe to leave a child or pet in a parked car?
No. Health Canada’s extreme heat guidance puts it in one word, “Never”, for anyone in your care, person or pet, left in a parked vehicle. It adds that a car can turn dangerously hot inside even when the day outside feels moderate. Tint doesn’t change that, and neither does a cracked window. Dog owners will find what film can and can’t do for a pet in tint and dogs in the car.
What can you do about the heat?
Park in shade when you can, use a windshield shade while parked, and put heat-rejecting film on the glass BC allows. The full routine, step by step, is in keeping a car cool through a BC summer.
Rear-glass film in LLumar ATC costs from $240 for most sedans and pickups, or $260 for a full-size SUV, with IRX ceramic as a per-package upgrade. See ceramic window tint in Langley or request a tint quote.
