The clouds might provide a bit of filtering coverage but it should be fine, I would give it a bit more time than usual to charge though. However if no light is actually hitting the stone then the radiating energy won't do you much good, it's suggested you relocate where your stone can a clear strong beam or wait for a better night.
Re: Charging Crystals
By: NimbleAsian / Beginner Feb 29, 2012
Post # 4
In my opinion, I think you can charge your crystals any time you want, but I know the full moon should give it more power. I charge mine with holy water, but I know some people do it with salt water or spring water. It's nice doing it with rain water too since it's coming from mother nature.