weather has 7 distinct synonyms spread across 3 of its 6 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
change under the action or influence of the weather
“A weathered old hut”
the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation
“they were hoping for good weather”
towards the side exposed to wind
Synonyms, antonyms and the broader and narrower relations for weather come from Princeton University’s WordNet. Full sources and licences.