夏衣[natsugoromo] summer clothes
夏羽織[natsubaori] summer haori (coat)
夏越し[natsugoshi] keeping over the summer
夏掛け[natsugake] summer-use futon
夏期学校[kakigakkou] summer school

夏期時間[kakijikan] daylight-saving time
夏期大学[kakidaigaku] university summer school
夏季休暇[kakikyuuka] summer vacation
夏菊[natsugiku] early chrysanthemums

炎暑[ensho] heat wave
寒暑[kansho] hot and cold
劇暑[gekisho] severe heat
厳暑[gensho] extreme heat
向暑[kousho] facing the heat

酷暑[kokusho] intense heat
残暑[zansho] late summer heat
暑い[atsui] hot (weather, etc.)
暑がり[atsugari] (person) sensitive to heat
暑さ[atsusa] heat (of the weather)