bad weather vs conditions

bad weather and conditions both are nouns.

Word	Noun	Adjective	Verb	Adverb
bad weather	Yes	No	No	No
conditions	Yes	No	No	No

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

bad weather: weather unsuitable for outdoor activities
conditions: the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation

Other hypernyms of bad weather include atmospheric condition, weather, weather condition.

bad weather (noun)	conditions (noun)
weather unsuitable for outdoor activities	the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation
	the set of circumstances that affect someone's welfare
	the prevailing context that influences the performance or the outcome of a process