The differences between modals is subtle
It can be cold in Stockholm in winter
means
It will certainly be cold in Stockholm at least some of the time
This is a statement about a general but not invariable state of affairs. You would say
Stockholm will get dark early in winter
because that is invariably the case
You would not say
It can be cold in Stockholm today
because what you mean is to assert a known fact
It is cold in Stockholm today
or else you mean to present what is no more than a probability
It may be cold in Stockholm today
If you want to make a prediction in which you have high confidence, you might say
It will be cold in Stockholm tomorrow
If you want to make a prediction in which you do not have high confidence or to provide a warning, you might say
It may be cold in Stockholm tomorrow