Afaik weather will become more extreme, so some regions will get very wet (flooding damage) (as we see currently with Portugal), and some very dry (drought).
From a physical viewpoint, climate change will heat up the oceans, so more energy will be available to lift up water into the atmosphere/clouds?
For rain to be useful it needs to be consistent and predictable.
If it only rains on 1 day a year, and on that day you receive 1 years worth of rain, it just washes all the soil away.
Building rainwater-storage-facilities for such sudden changes in rain patterns is hard as well.