暖 - The Sun Is on the Left, My Friend Dan Must Be Warm

Readings & Meanings:

あたた（−かい）

ダン

warm (weather), warm (emotion)

Common Usage:

暖房

暖める (trans.)

暖まる (intrans.)

Examples:

暖房を使って、部屋を暖める。

また空気が暖まる。

Translations:

Using the heater, I'll warm up the room.

The air is getting warm again.

Bonus:

地球温暖化　（ちきゅうおんだんか）is a word for global warming, and it uses both 温 and 暖!

地球 means Earth

温暖 means warmth

化 means action, so it's the action of making the Earth warm. Awesome! (but only awesome for studying... not actually awesome in real life)

Important:

Don't get confused with 温!

暖 is for weather and for friends. In the kanji, if you squint, you can see both 天気's 天 and 友達's 友.

References:

http://www.thejapanesepage.com/kanji/kanji/a.htm