I heard someone said "yesterday was raining, so I didn't go outside of house", which seems to be a misuse.
per this post
To describe what is actually happening right now, you use the verb form:
It is raining.
To describe the sort of day it is, you use the adjective form:
Today is a rainy day.
it is the sort of day (rainy) that causes the speaker I didn't go outside of house, so the rainy is more appropriate, right?