The best way, of course, is to check your favorite source for local weather.
There are some ways to guess that it'll snow, but by the time you do it will almost be happening, and you could save yourself time by checking the above.
Before a storm, typically you get get high cirrus that gradually lower - it may start with mid-level altostratus or altocumulus that lower and eventually turn into a grey overcast. It will often warm up closer to freezing if it has recently been warm, for dynamic reasons I won't get into. Actually, people who live off the land such as natives of the Arctic, are quite good at predicting the onset of storms.
Some people claim there is a smell to the air. I don't know how much truth there is to that, or why it would be true.
Look at the weather forecast. Really, that's the best thing to do these days when there is so much data out there, especially from the upper atmosphere that is input into advanced computer models. Storms can be forecast if you have the tools so much better than just looking at the sky. If for some reason this is not possible, snow storms come in the same way most others do - high cirrus a day or two in advance, then altostratus (midlevel clouds) which lower to nimbus and begin to darken and precipitate.
With a weather rock
this is an acient way to tell weather with a rock hanging on a string from a tripod
if the rock is wet it is raining
if the rock is moving its windy
if you can see the rocks shadow its sunny
if the rock has ice on it its snowing
if the rock is in a big crack in the ground theres been an earthquake
if the rocks covered in sand theres been sandstorm
if the rock is swirling above you TAKE COVER thers a tornado in your area
approaching strong low-pressure system. These conditions often occur when a cold front is moving into an area, bringing unstable atmospheric conditions with it. Wind and thunderstorms are common along and behind the cold front as the contrasting air masses interact.
The appearance of cirrus clouds is an early sign of an approaching warm front.
The air behind a cold front is noticeably colder and drier than the air ahead of it. When a cold front passes through, temperatures can drop more than 15 degrees.
cirrus clouds
Thunder storms occur when hot air and cold air run into each other. Therefore one way of predicting them is if you notice a cold front has come during warm weather, or a warm front during cold weather.
Bob Kudzma is reporting on a cold front approaching, which may cause it to snow!
A cold front approaching Texas from the north.
approaching strong low-pressure system. These conditions often occur when a cold front is moving into an area, bringing unstable atmospheric conditions with it. Wind and thunderstorms are common along and behind the cold front as the contrasting air masses interact.
The appearance of cirrus clouds is an early sign of an approaching warm front.
If you know that a warm front is approaching, you can forecast when it will rain, and can cancel a barbecue. The warm front may have collected a lot of moisture as it passed over the ocean. Then, if it meets a cold front, rain will fall, or snow if in winter.
A warm front is likely approaching if you see cirrus clouds high in the sky. These clouds are indicators of an advancing warm front because they form at high altitudes where warm air is being lifted over the cooler air present ahead of the front. This lifting of warm air can produce cirrus clouds, which are composed of ice crystals and are often thin and wispy in appearance.
Three triangles on a weather map typically indicate a cold front, which is a boundary where cold air is advancing and replacing warmer air. This can result in changes in weather conditions such as temperature drops, wind shifts, and precipitation.
The air behind a cold front is noticeably colder and drier than the air ahead of it. When a cold front passes through, temperatures can drop more than 15 degrees.
A cold front is typically represented by a blue line with triangles pointing towards the warmer air mass it is approaching on a weather map.
cirrus clouds
you are approaching head on.
Thunder storms occur when hot air and cold air run into each other. Therefore one way of predicting them is if you notice a cold front has come during warm weather, or a warm front during cold weather.