Before it can snow the temperature has to be at least 32 F degrees and anything above that the snow is likely not gonna happen.
Although the temperature up in the air can be colder so it may snow when the temperature on the ground 40 F which I have seen that happen a few times.
But usually the temperature needs to be at least 32 F or lower before it will snow and stick to the ground.
Snow forms when the atmospheric temperature is at or below freezing which is 32 F and there also has to be a minimum amount of moisture in the air for it to snow.
When the ground temperature is at or below freezing, the snow will reach the ground but if not the snow may dissipate and melt before it hits the ground.