Water freezes at 273.15 K (0 °C, 32 °F) - but can be supercooled (undercooled) without becoming a solid at standard pressure down to almost 224.8 K (−48.3 °C, −55 °F) if it is pure and free of nucleation sites.
Vapor pressure of supercooled water:
Supercooled Water - Vapor Pressure vs. Temperature
The Engineering ToolBox (2014). Supercooled Water - Vapor Pressure vs. Temperature. [online] Available at: https://www.engineeringtoolbox.com/water-supercooled-vapor-pressure-d_1910.html [Accessed Day Month Year].