To Fall
To Come Down
intransitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means descend, but this word means something closer to to fall or to come down. Usually used with things like rain or snow.
The rain is to fall and you're outside anyway with your mouth open so you'll get a mouth full (ふる) of rainwater! All the ponds, wells, and your yard will be full of water too!
お昼過ぎ、にわか雨が降る中、私は愛犬の散歩をしていました。
I was walking my dog in the afternoon while the rain fell.