WordNet records no synonym and no antonym for weatherliness. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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.
(of a sailing vessel) the quality of being able to sail close to the wind with little drift to the leeward (even in a stiff wind)
“the Spanish ships had superior speed and weatherliness”
Synonyms, antonyms and the broader and narrower relations for weatherliness come from Princeton University’s WordNet. Full sources and licences.