autumnal chill; touch of cold in the air
Refers to the first noticeable coldness of autumn, often with a poetic or seasonal nuance. Used in weather descriptions and seasonal greetings.
I've started to feel the autumnal chill in the mornings and evenings.
秋寒の折、お体を大切に。
Please take care of yourself in this chilly autumn weather.
Compound of 秋 (autumn) and 寒 (cold). The reading あきさむ is a straightforward kun'yomi combination.