I have also left mine loaded for a few days at a time for the same reason as you were asking. If you have a safe place to keep it where it is cool and dry, that is the best.
Like in yourvehicle or unheated garage, shed etc.
That way there's less of a chance of the powder getting damp from condensation forming.
The condensation thing can happen if you take it from one extreme temp to the other.
So far I've not had a "no-fire" or "hang-fire".

But like others said. If it's raining or extremely damp, you may want to pull the charge if possible. I realize this can be pain if you are not shooting an inline. But if the powder gets too damp, you may miss the "BIG ONE" if it goes"pop" instead of "BOOM" !!!!

Hope this helps...

chris