noun
warmth; warm weather
Refers to warm air, warmth, or mild weather, often in contrast to cold. Can be used for both literal warmth and the pleasant feeling of spring-like weather.
春の暖気が心地よい。
The warmth of spring is pleasant.
暖気が流れ込んで、気温が上がった。
Warm air flowed in and the temperature rose.
Compound of 暖 (warm) and 気 (air, atmosphere). The reading is on'yomi.