Their sides are unprotected so a gust of sideway wind can bring rain in.
They will need to hunt around Inazuma for these hidden gems hidden all around the region, and they will need to turn in 180 in total to gain all the rewards.
Valleys can be especially troublesome, because they carry a lot of water during heavy rain.
Preview the sound in the description below.
Imagine the electronics stored there getting water-damaged.