

今日はとても暑いです。
東京の夏は暑いですか。
暑い日は水をたくさん飲みます。
"あつい(暑い)" is in the lesson "Hot weather" (Level 15), along with 12 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.