You have some very fun monster designs and a fun idea. It's pretty brutal which is fine for a Hack N' Slash but I do have some criticisms.
I don't like the weather mechanic, it seems to be too punishing if you don't wanna deal with storm weather (or just crappy control weather which is what it is) then you take damage and you have no way of healing throughout all 5 levels. At least none that I could find. This forces you into almost always staying in storm weather where the movement controls are very annoying.
I wouldn't hate it, if you had to use it occasionally, maybe where Storms healed you and clear weather damaged you.