noun
long night; long autumn night
Refers to the lengthening nights, especially in autumn. Often used in poetic or literary contexts. Compare with 日永 (ひなが, long day in spring).
See also: 日永
秋の夜長に読書を楽しむ。
I enjoy reading on long autumn nights.
夜長の季節になると、つい夜更かししてしまう。
When the season of long nights arrives, I end up staying up late.
Refers to long days, especially in spring. 夜長 is its autumn counterpart.
Compound of 夜 (yo, 'night') and 長 (naga, 'long'). The reading よなが is a standard kun'yomi combination.