Summer is when most people expect a chip to crack. Valley highs often top 100°F, and a hot windshield hit with cold A/C is a classic way to lose a windshield. But fall brings its own risk. The heat backs off, the nights cool down, and the daily swing in temperature keeps working on any chip you haven't fixed.
Why do chips spread when the temperature changes?
Glass expands as it warms and shrinks as it cools. When the whole windshield changes temperature evenly, that's fine. When one area changes faster than another, the glass is pulled in two directions. A chip is the weakest point, so that's where a crack starts.
A laminated windshield is two layers of glass with a plastic layer between them. A chip usually breaks the outer layer, leaving sharp edges inside the break. Stress concentrates at those edges. Our guide on why rock chips spread in heat covers the physics in more detail.
Is fall weather really a problem in the Temecula Valley?
Yes, because of the day-to-night swing. Inland valleys like ours can see warm, sunny afternoons followed by much cooler nights. Your windshield goes through that cycle every day, and the sun-facing glass heats unevenly while the car is parked.
On top of that, fall is when driving habits change:
- Defroster season starts. The first cold mornings send people straight to full-blast heat on cold glass.
- A/C is still on in the afternoon. A car parked in the sun can still get hot inside, and a blast of cold air hits warm glass.
- Santa Ana winds kick up. Dry wind carries grit and debris that cause new chips. See Santa Ana winds and your windshield.
How should I use the defroster on a chipped windshield?
Start low and let it build. A gentle, gradual warm-up is much easier on a chip than hot air aimed at cold glass.
- Start the car and set the fan low with the temperature on cool or mild.
- Let the engine warm up and raise the temperature slowly over a few minutes.
- Aim the vents at the windshield only once the air is warm, not hot.
- Use the A/C button with the defroster to pull moisture out of the air. Most cars do this automatically.
- Never pour hot water on a frosted windshield.
We cover a full cold-morning routine in hot defroster on a cracked windshield.
How should I use the A/C on a hot afternoon?
Cool the car down before aiming cold air at the glass. Open the windows for a minute to let hot air out, start the A/C on the floor or face vents, and switch to the windshield only once the cabin has cooled. Parking in shade or using a sunshade cuts the temperature difference in the first place.
What else can make a chip crack in fall?
- Car washes. Cold rinse water on a sun-warmed windshield.
- Bumps. Speed bumps, potholes and rough roads near construction flex the glass.
- Door slams. A sharp jolt and pressure change.
- Waiting. Every day a chip sits, it collects dirt and goes through another heat cycle.
Should I repair a chip now or wait until it cracks?
Repair it now. A chip smaller than a quarter that isn't in your line of sight or at the edge can usually be filled in about 30 minutes. Once it becomes a long crack, you're usually looking at a new windshield.
Our rock chip repair starts at $98, with $25 for each additional chip on the same visit. We come to you anywhere in our service areas. Text a photo of the chip to (951) 364-2300 for a price.
If you're not sure whether yours is repairable, see repair or replace.