cloudy weather during the herring season near Hokkaido
A traditional seasonal term for overcast skies common along the Hokkaido coast from the third to the sixth lunar month, when herring fishing was active. Now mostly a historical or regional weather expression.
Along the coast of Hokkaido, overcast skies called nishingumori sometimes persist in early spring.
Compound of 鰊 (にしん, 'herring') and 曇り (くもり, 'cloudiness'), referring to the cloudy weather typical during the herring fishing season in Hokkaido.