Will Water Freeze at 27 Degrees? A Look at the Science

Yes. Pure water freezes at 32 °F (0 °C) at standard atmospheric pressure, so 27 °F (about −2.8 °C) is below its freezing point. Water can freeze at that temperature, though the air temperature alone cannot tell you how quickly.

What affects freezing

Water needs to lose heat before it turns to ice. The time depends on factors such as the amount of water, the container’s shape, and how much heat the water receives from its surroundings. A shallow layer generally cools faster than a deep container, but there is no fixed freezing time for a given air temperature.

Dissolved substances such as salt can lower water’s freezing point. As a result, salty water may remain liquid at 27 °F. Ordinary fresh water in a still container, by contrast, can freeze at that temperature.

One example

A shallow tray of fresh water left outside on a night when the air is 27 °F may develop ice. A larger, deeper container may take longer to freeze because it holds more water and loses heat at a different rate. The actual result depends on conditions such as the container, exposure, and temperature of the water at the start.

The key distinction is that 27 °F air makes freezing possible; it does not mean every body of water will freeze immediately or completely. Water can also remain liquid briefly below its usual freezing point under some conditions.

Key Takeaways

• Pure water freezes at about 32 °F (0 °C) at standard atmospheric pressure.
• 27 °F is about −2.8 °C, below water’s usual freezing point.
• Water may freeze at 27 °F, but the time and extent depend on the amount of water and its surroundings.
• Dissolved salt or sugar can lower the freezing point.