mildness vs good weather

mildness and good weather both are nouns.

Word	Noun	Adjective	Verb	Adverb
mildness	Yes	No	No	No
good weather	Yes	No	No	No

As nouns, good weather is a hypernym of mildness; that is, good weather is a word with a broader meaning than mildness:

mildness (noun)	good weather (noun)
mercifulness as a consequence of being lenient or tolerant	weather suitable for outdoor activities
acting in a manner that is gentle and mild and even-tempered
good weather with comfortable temperatures