mild late autumn day; Indian summer day
Refers to a warm, calm day in late autumn (around November), similar to an Indian summer day. Often used in the phrase 小春日和 (こはるびより).
See also: 小春
Today is a mild late autumn day, and it feels very pleasant.
The mild late autumn days continue, and the garden flowers are still blooming.
Compound of 小春 (こはる, 'little spring', referring to a warm period in late autumn) and 日 (ひ, 'day'), with rendaku voicing of ひ to び.