This one, “rain comes,” is a direct translation of the Korean expression “비 온다”. In English however, the words “rain” and “snow” are also verbs, so they don’t need an extra verb like “comes.”
Instead, simply say, “It is raining,” or “It is snowing.” If the rain/snow is predicted, then you can try, “It will rain tomorrow,” or “It’s supposed to snow tomorrow.” Other examples include, “It might rain this weekend,” “There’s a 30% chance it will snow tonight,” or “It will stop raining this afternoon.”
If you try and translate “비 온다” as, “Rain is coming,” it does NOT mean it is currently raining, as in the Korean expression. Instead, it means there is rain in the forecast and it might rain LATER, but it is not raining NOW. Please be careful of this important difference.