1. It's nice and warm today. 2. It's absolutely boiling! (boiling = extremely hot) 3. We're having a real heat wave. (heat wave = many consecutive days of hot weather) 4. The sun's really strong today. 5. It's hot and humid.
Indoor rowing on ergometer, or tank is a way to train technique and strength by going through the same motions as rowing, with resistance. Indoor rowing is helpful when the lake is frozen, or there are no lakes near by.