I was curious and so group.googled for {window heat break car}. See, for
starters, the first two threads at

http://groups.google.com/groups?q=wi...ie=UTF-8&hl=en

It apparently does happen often enough that I'd be inclined to believe heat can
do this (via several possible mechanisms, ranging from a flaw to temperature
differentials from edge to center, to maybe water splattering on a hot car
window... )

"Joan" <rosskat@pipeline.com> wrote
> We only had our Honda crv for a year now. The front windshield was replaced
> when a crack caused by a stone that hit the window. That has happened with
> other vehicles before.
>
> Now yesterday it was high 80's and very humid heat -----after work I
> went to the car ( sitting in employee parking lot from 6 am to 4 p.m. ) to
> find the 2nd side passenger window ( tinted dark glass ) completely busted
> and in splinters. I did call the cops prior to the insurance co. Nothing
> taken out of the car and the officer felt the window just busted from the
> heat.
>
> I was wondering how often that happens.? I have other cars ( not Honda's )
> in the past with never a window busted from the heat.
>
> Any similar experience? And should one keep windows open a crack in extreme
> heat. ? Or would turning on the AC in a hot car cause the window to crack??
> Just wondering