At what temperature does wine freeze?
Barello is a home cellar and bar app that tells you what to open tonight, what to keep, and what you can mix from what you have. A typical red wine starts to freeze at about 22°F (−6°C), according to the University of Illinois physics department. The alcohol is what keeps it liquid below water's 32°F (0°C).
Why there's no single number
The more alcohol a wine has, the colder it has to get before it freezes, and sugar and everything else dissolved in it lower the point a little further. A typical wine at 12.5% alcohol sits near 22°F (−6°C); a stronger or sweeter one, lower.
It doesn't freeze solid all at once, either. The first ice to form is almost pure water, which leaves the rest of the wine stronger and harder to freeze, so a bottle goes to slush long before it goes to ice.
The freezer and the car
A home freezer runs well below 22°F (−6°C), so a bottle forgotten in there will freeze, and one left in a car on a cold night can too. Freezing can damage it: the wine expands as it freezes, which can push the cork out or crack the glass, and once the seal goes, air gets in, and air is what spoils wine (Wine Spectator).
If a bottle does freeze, let it thaw, then check the cork and the glass. A cork that has moved may have let air in, and the only way to know whether the wine survived is to open it and taste it. Small crystals in the bottle are tartrates, which the Australian Wine Research Institute says pose no health risk.
Heat does its damage more slowly and out of sight. A warm spot keeps a wine ageing faster all the time it sits there, and at 77°F (25°C) or more it's spoiling. How to store wine without a cellar puts a number on every spot in the house.
More on temperature
The full chart, storing and serving, is on wine temperature.