the nectar of some plants seem to have a higher moisture content than others when condensed to make honey. As a general rule the percentage of these plants contribution to the overall honey crop is not enough to be a problem with the combined nectars from all sources yielding a honey with a water content of 18-18.5%. However, during times of unusual weather such as drought when some plants may not produce any or little nectar or in the case of excessive rain some plants may produce an abundance of deluded nectar. During such times the honey that results with honey with a water content as low as 16% in the case of drought, or as high as 20% in the case of excessive rain.
An example of this phenomenon may be that honey harvested within two weeks of an extended rainy period might yield a cured honey with a higher than usual water content. Whereas, the honey harvested after a period without rain might result in a cured honey with a lower than normal water content.
It is a condition quite common here in the Pacific Northwest due to our varying weather patterns. I would imagine that humidity levels present in the atmosphere would have some affect on the water content of cured honey maybe making it impossible for the bees to render a lower water content in the case of continued excessive humidity.
Plants that have a natural high water content nectar, such as ragweed, will usually crystalize or ferment rapidly and should therefore be used for the making of mead or whipped (creamed) honey.