When we think about vehicle maintenance, it’s easy to focus on oil changes, tire rotations, or brake pads. But one thing that often gets overlooked is how much of a beating your windshield takes — especially in extreme temperatures. Whether it’s the heat of a Toronto summer or the deep freeze of our winters, temperature extremes can have a serious impact on your windshield and the sealant that keeps it in place.
As a team that’s been in the auto glass business for years, we’ve seen firsthand how our city’s weather can stress out a windshield. If you’ve ever noticed a small crack that suddenly got bigger overnight or a strange whistle coming from your windshield during a cold snap, you’re not imagining things. It’s all connected to how your auto glass and sealant react to temperature swings.
Why does temperature matter for your windshield ?
Your windshield is made of laminated safety glass, which means it’s actually two layers of glass with a plastic interlayer. This design helps absorb impacts and prevent the glass from shattering. The sealant — usually a strong adhesive like polyurethane — bonds your windshield to your vehicle’s frame, keeping everything watertight and secure.
But here’s the thing: both glass and sealant expand and contract with temperature changes. And when the changes are extreme or sudden, problems can start to pop up.
What happens in hot weather ?
In the summer, your car can feel like a sauna. Interior temperatures can rise to well over 60°C (140°F), especially if you’re parked in direct sunlight. This heat doesn’t just make your seats uncomfortable — it also affects your windshield and the sealant around it. In fact, we often remind drivers that prolonged exposure to the sun causes windshield damage in more ways than one.
We often see issues like:
- Thermal expansion: The windshield glass can expand in the heat, creating pressure against the sealant and the frame.
- Sealant softening: High heat can cause sealants to soften slightly, especially if they’re already aging or weren’t applied properly. This can lead to gaps or a weaker bond over time.
- Chips turning into cracks: That tiny rock chip you ignored last month? Heat can cause it to spread fast. We always recommend fixing chips before summer hits.
If you notice your windshield making new noises while driving or find moisture building up around the edges, it could be time to get it checked out.
What happens in cold weather ?
Toronto winters aren’t easy on any part of your car, and your windshield definitely feels the chill. Cold weather causes materials to contract, and the transition from a freezing windshield to a blasting defroster can cause rapid temperature changes that lead to damage.
Common cold-weather issues include:
- Sealant becoming brittle: When temperatures drop, the sealant can lose flexibility, making it more likely to crack or separate from the frame.
- Stress cracks from rapid defrosting: We’ve seen many windshields crack when someone turns their defroster on full blast on a -20°C morning. The sudden temperature change creates stress points that lead to cracking.
- Leaks: Shifting sealant and contracted materials can create small gaps, which lead to water leaks — a big pain in the middle of winter.
If you ever see fog between the layers of your windshield or hear wind whistling around the edges, give us a call at (416) 666-7345. These are signs your sealant might be compromised.
To protect your windshield from these harsh winter effects, check out our 5 Tips to Maintain Your Car’s Windshield in Winters for simple but effective ways to keep your glass strong and safe all season long.
Why does sealant quality matter ?
At National Auto Glass, we only use high-quality OEM-approved sealants for our installations and replacements. Not all sealants are created equal, and lower-grade products can break down faster under temperature stress. That’s why choosing experienced installers (like us!) matters. We make sure your windshield is installed to stand up to Toronto’s changing seasons.
And if you’ve recently had windshield work done but are noticing leaks or noises, don’t hesitate to reach out. It could be a sign the previous job didn’t account for temperature-related expansion and contraction.
Protecting your windshield year-round
We always remind our customers that a little care goes a long way when it comes to auto glass. Here are a few things we recommend:
- Park in shade during summer when possible — it helps keep internal temperatures down.
- Use your defroster gradually in winter to avoid thermal shock.
- Fix chips early before they grow into cracks.
- Schedule seasonal inspections if you’re noticing anything unusual with your windshield.
And if you’re ever unsure, don’t worry — we’ve got your back. We offer expert windshield repair in Toronto, and our team is always happy to take a look if something doesn’t seem right. Whether it’s a minor chip or a full replacement, we’ll help you find the best solution.
Give us a call anytime at (416) 666-7345 or book an appointment or ask us a question. We’re here to make sure your windshield is in top shape, no matter what the temperature is outside.
