暑い / 熱い / 厚い — three homophones, three completely different domains

Worth pinning for beginners who still mix these up at N1 review time: 暑い is exclusively ambient/weather heat (今日は暑い). 熱い is temperature you can touch or feel directly, AND figurative passion (お茶が熱い, 熱い議論). 厚い is physical thickness of an object, AND figurative depth of feeling toward a person (厚い友情 'deep friendship', 面の皮が厚い 'thick-skinned/shameless'). None of the three kanji are interchangeable even though they're all read あつい.