Can spraying water on a hot windshield cause it to crack?

In my experience, yes it can. If the screen is iced up, spraying water that has a large temperature difference can cause rapid expansion in the glass causing it to crack or even shatter. An iced windscreen will be at about 0 degrees. Water from an outside hose will be about 4 degrees. This doesn't sound much but equates to a 400% increase in paratical terms. Better to turn on the motor and demister, allowing the slow increase in temperature clear the screen. This will also allow the engine oil to work around the engine before drive strain is put on it.This also applies when spraying cold water onto a hot windscreen.