How cold does it have to be to snow?
The temperature at which it snows depends on several factors, including the type of snow and the altitude.
For snow to form, the air temperature must be below freezing (32°F or 0°C) and there must be moisture in the air. If the air temperature is at or below freezing and there is enough moisture in the air, snow will form as ice crystals. The more moisture in the air, the more snow will fall.
However, it’s not only the air temperature that determines if it will snow. Snowflakes form when water vapor freezes into ice crystals around a particle, called a nuclei. These nuclei can be dust, pollution or other particles in the air. If the air is dry, there may not be enough nuclei for the water vapor to freeze around, and it may not snow even if the temperature is below freezing.
Additionally, the altitude plays a role in the snow formation, because as you go higher in altitude, the temperature drops, which means that it can snow at lower temperatures at higher altitudes than at lower altitudes.
In general, snowfall typically occurs when the temperature is at or below 20°F (-6.6°C) and there is sufficient moisture in the air. However, it’s not uncommon for it to snow at temperatures slightly above freezing if the air is moist enough and if the ground temperature is below freezing.