Why Windshields Crack More in Summer (and How to Prevent It)

Summer is a season of warmth, sunshine, and outdoor adventures. It also brings a common automotive headache: cracked windshields. Many vehicle owners notice that their windshields are more prone to cracking or chipping during the hotter months. Understanding why this happens and learning how to prevent it can save you time, money, and potential safety hazards.

The Science Behind Windshield Cracking in Summer

Windshields are made of laminated safety glass, which consists of a layer of plastic sandwiched between two sheets of glass. This construction is designed to hold together even when cracked, providing safety and durability. Still, extreme heat can pose a threat.

1. Rapid Temperature Fluctuations

One of the primary reasons windshields crack more in summer is rapid temperature changes. On scorching days, the interior of a vehicle can heat up dramatically if left in the sun. In some cases, the interior can reach over 150˚F (65˚C). A sudden plunge in temperature—like pouring cold water on a hot windshield or entering an air-conditioned car from the outdoors—causes the glass to expand and contract quickly. These repeated stresses weaken the glass over time, making it more susceptible to cracks and chips.

2. Thermal Stress and Material Fatigue

Continuous exposure to high temperatures without proper ventilation or sun protection exacerbates thermal stress. Over time, the repeated expansion and contraction can cause microscopic cracks that eventually develop into larger fractures. Sunlight’s UV rays can also degrade the adhesive bonding the layers of glass, weakening the windshield’s integrity.

3. External Factors and Hazards

Summer also means increased outdoor activity, more debris, and a higher risk of minor impacts from things like gravel on the road, falling tree branches, or other debris. The heat can make existing damage worse and create a domino effect.

4. Existing Chips and Cracks Worsen

The heat of summer can turn minor chips into larger cracks. A small chip or crack that is insignificant during cooler months can be exacerbated by heat. The stress from temperature fluctuations causes the crack to spread, especially if the crack was already present but unnoticed.

How to Prevent Windshields from Cracking in Summer

While some factors are beyond your control, proactive measures can minimize the risk of cracks and extend the life of your windshield.

1. Use Sunshades and Car Covers: Whenever possible, park in shaded areas or use a sunshade to block direct sunlight. A car cover can also prevent the interior temperature from soaring. Lower interior temperatures reduce thermal stress on the glass.
2. Ventilate Your Vehicle: Before driving after parking in the sun, open the windows for a few minutes to help equalize the interior and exterior temperature. Using the air conditioning set to a low temperature initially can also prevent sudden temperature shocks.
3. Avoid Rapid Cooling or Heating: Don’t pour cold water on a blazing hot windshield or blast high heat from the car’s A/C immediately after starting the engine in the heat. Gradual cooling helps minimize stress.
4. Address Chips and Cracks Promptly: Repair minor damage as soon as it occurs. Small chips can often be fixed quickly by a reputable auto glass service. This will prevent them from expanding in the heat. If cracks develop, seek professional repair or replacement before they worsen.
5. Maintain a Safe Distance: Keep a safe distance from road debris, particularly in construction zones or on gravel roads, as flying particles can cause chips or cracks that may grow in the heat.
6. Regular Inspection: Check your windshield regularly for small chips or cracks, especially before summer. Early detection allows for timely repairs, preventing larger issues down the road.

Do You Have Windshield Damage in Gainesville, GA?

If you live, work, or are passing through Gainesville, Flowery Branch, or Winder, GA, and discover damage to your windshield, contact us at New York Auto Glass. We offer insurance claims assistance, as well as in-shop and mobile service, so you don’t have to interrupt your day for windshield repairs.