Is Water Frozen at 27 Degrees Fahrenheit? Quick Answer
No, water is not frozen at 27 degrees Fahrenheit. The freezing point of pure water at standard atmospheric pressure is 32 degrees Fahrenheit (0 degrees Celsius). At 27 degrees Fahrenheit, pure water remains a liquid, though it will be supercooled and can freeze instantly if disturbed.
Why 27 Degrees Isn’t Frozen
The freezing point of water is a fixed physical property, not a range. Pure water freezes at 32°F (0°C) at sea level. At 27°F, the water is colder than its freezing point but still liquid — a state called supercooling. This happens when water lacks a nucleation site (a tiny particle or rough surface) for ice crystals to form. A sudden jolt, vibration, or dust particle can trigger rapid freezing.
For example, a bottle of purified water left in a freezer at 27°F will stay liquid. If you tap it or pour it over an ice cube, it will freeze instantly into slush. This is a common science demonstration, not a contradiction of the freezing point.
How Impurities Change the Number
Tap water, lake water, or seawater rarely freezes at exactly 32°F. Dissolved minerals and salts lower the freezing point through freezing-point depression. Seawater, which has a salinity of about 3.5%, freezes at roughly 28.4°F National Weather Service. That is still above 27°F, but only barely. If the water contains enough antifreeze compounds — like the ethylene glycol in car coolant — the freezing point can drop well below 27°F.
Consider a winter road treated with salt. The brine solution on the pavement can remain liquid at 27°F because the salt has depressed the freezing point. If you measure the temperature of that puddle with a thermometer, it will read 27°F, and it will be liquid. The same water without salt would be solid ice.
Key Takeaways
- Pure water freezes at 32°F (0°C); 27°F is below that point, so pure water is supercooled, not frozen.
- Supercooled water is unstable and will freeze instantly with a disturbance like a vibration or dust particle.
- Dissolved salts and minerals lower the freezing point; seawater freezes around 28.4°F, and salt-treated roads stay liquid at 27°F.
- Antifreeze compounds can drop the freezing point far below 27°F, so the answer depends on the water’s purity.
