expression, noun-modifying (irregular)
Prenominal phrase describing a period or place with frequent or heavy rain. Often used with words like 日, 季節, 地域.
雨の多い日が続いています。
Rainy days have been continuing.
この地域は雨の多い季節に入った。
This region has entered its rainy season.
Phrase composed of 雨 (rain) + の (attributive particle) + 多い (many, frequent). The exact origin as a set phrase is uncertain, but it follows a common pattern for descriptive prenominal expressions.