Rain is precipitation that has melted after it has fallen a certain distance from cloud level. It's liquid water, unlike other kinds of precipitation, like sleet, hail or snow.

[He pauses.] Do... do you know what clouds are, Ms. Sayo? If not, I would be happy to explain them to you.

Also, you might want to find somewhere drier to stay, though the rain is entirely harmless... do you need assistance, or are you alright where you are?