• 暖房だんぼう — heating
• 温暖おんだん — mild (climate)
• 暖流だんりゅう — warm ocean current
• 寒暖かんだん — temperature variation
• 暖気だんき — warm air
• 暖あたたかい — warm (temperature or feeling)

The kanji 暖 combines the 日 (sun) radical and the phonetic 段 (ダン), forming the idea of sunlight warming something. It’s often used in reference to temperature, climate, or feelings of comfort and warmth.

While 温 refers to warmth in general (including temperature of objects or people), 暖 emphasizes atmospheric warmth or emotional warmth.

今日きょうは 暖あたたかくて 気持きもちが いいです。
It’s warm and pleasant today.

冬ふゆには 暖房だんぼうが 必要ひつようです。
In winter, heating is necessary.