With high summer temperatures, it should be noted that the layers of laminated glass in a car’s windscreen expand when exposed to the heat. However, if cold water is suddenly applied to the windscreen, the thermal shock can cause the layers of glass to contract unevenly, causing a crack to form and spread across the screen.

If a windscreen needs cleaning, or you are using a car wash in the heat, it is always advisable to ensure the car glass is cool before applying cold water.