What is the lowest temprataure at which it can snow?

Question

I have heard that it cannot snow if the temprature is in the 20's or lower. I just want to know for sure for once and for all!

Answer 1

It was -20 degrees F in Laramie, Wyoming last night, and they got some snow. I think that must not be too far from the limit, though. I grew up in Wyoming, and when the temperature got much under -30 degrees F, the capacity of the atmosphere to hold moisture dropped to the point where it couldn't snow anymore.
Was that cause or effect? I don't know. Cloud cover would cause the air to retain heat, and so on. I just remember that I always hated crystal clear mornings during the winter, because I knew I was going to freeze my **** off.

Answer 2

It absolutely can snow less than 20 degrees F. It snows at below 0 degrees F with ease ( the flakes are usually smaller at that temp. but it can build up in drifts just as easy as 20 degree snow. When it gets very cold such as less than -10 degrees F it is usually a clear sky and there is no moisture to make snow so you see less at these colder temperatures. (only because of the lack of clouds not the temperature.)

Answer 3

There is no such temperature. It becomes less and less likely at lower temperatures (because it's drier) but it never becomes impossible. And snow that falls at lower temperatures tends to be drier (fluffier).

Answer 4

At temperatures below about 23ºF (-5ºC), individual snow crystals sometimes fall. Aggregated flakes rarely fall when the temperature is below 0ºF (-18ºC) and never below -33ºF (-36ºC). So you might be justified in saying it can be too cold for snowflakes to fall, but not justified to say it's to cold for snow to fall. Snowfall composed of individual snow crystals is sometimes called "diamond dust" if it sparkles in the sunlight, or "flour snow" if it does not.

At temperatures around -40º (on either scale), water droplets generally freeze even without active ice nuclei by a process called homogeneous nucleation. Without the presence of rapidly evaporating liquid droplets, crystals will grow by deposition very slowly and will have trouble growing to a size large enough to overcome cloud updrafts and fall to the ground. However, some crystals will by chance sublimate, and the vapor produced can be deposited on other crystals until a few of them are big enough to fall. If the updrafts are very weak, then very small crystals, often called snow grains, can fall despite their small size. In Japan, crystals as small as 0.07 mm (not much bigger than fog droplets) have fallen. Surprisingly, in very cold climates, particularly Antarctica, snow does not always fall from visible clouds, but from an apparently clear sky. This may involve a process called self-nucleation, in which vapor molecules come together by chance without benefit of a nucleus. This sort of snowfall is extremely light, but it can continue for days on end. I have seen anecdotal reports of this sort of snow often falling at or below -58ºF (-50ºC) in Antarctica, but I have been unable to find official records to confirm this.

So what is the official world record for the coldest temperature at which snow has fallen? I'll be damned if I can find out. It seems that meteorologists don't bother to keep records like that. They obviously have no sense of priority. I took matters into my own hands and searched twelve years of daily records for Fairbanks, Alaska, a city that has cold yet reasonably snowy winters. The coldest snowy day I could find was February 4, 1999 when just a trace of snow fell at a temperature no higher than -42 F (-41ºC), which was that day's high temperature; the low was -55 F (-48ºC). I'm sure that's not any kind of record, but it's the coldest I could find without ruining my eyes poring over weather data. If a trace isn't good enough, then on January 6, 1998, a whopping 0.4 inches fell at a temperature no higher than -35 F (-37ºC), which was that day's high temperature; the low was -41. Certainly ice crystals can form at much colder temperatures than that. Cirrus clouds are composed of ice crystals as low as -85ºF (-65ºC), but these crystals do not fall to earth. Snow crystals have been created in the laboratory down to at least -112ºF (-80ºC).

So, to sum up, at temperatures near freezing, you can expect big honking snow flakes and lots of them. One those comparatively rare occasions when it snows near 0 F, you can expect individual snow crystals, but not very many of them because such cold air can't "hold" as much water vapor. Below about -40º, you can expect only very small crystals to fall, and very few of them at that. So the next time somebody tries to tell you it's too cold to snow, check the thermometer. If it's warmer than forty below, send them up Fairbanks way, and they'll never doubt you again.

Answer 5

the lowest temperature its ever been was at around -50 something, (in siberia)