"Pure water normally freezes at 273.15 K (0 °C or 32 °F) but it can also be "supercooled" at standard pressure down to its crystal homogeneous nucleation at almost 231 K (−42 °C).[1] If cooled at a rate on the order of 10^6 K/s, the crystal nucleation can be avoided and water becomes a glass. Its glass transition temperature is much colder and harder to determine, but studies estimate it at about 165 K (−108 °C).[2] Glassy water can be heated up to approximately 150 K (−123 °C)" - bob