Are you worried about direct exposure to water, or just the increased humidity? My best guess is that you really don't want water coming into contact with your floor at least until the solvent has fully evaporated. At that point, your floor will still be "curing" but not "drying" per se.
As far as the maximum (airborne) humidity, surely your product literature has guidelines for both this and temperature extremes. Again, just speculating but once your floor has gotten to the tack-free/"light foot traffic" stage, it will probably not be greatly affected by some moisture in the air.
(Disclaimer: I am not a professional, but I have successfully used solvent based epoxy to do several garages... perhaps somebody could give you better information or a more informed opinion if you named the exact product you are using and the exact weather conditions you are expecting.)