Definition of Septemberish in English:
Septemberish
(also Septembrish)
adjective sɛpˈtɛmbərɪʃsəpˈtɛmbərɪʃ
Of, resembling, or characteristic of September.
Origin
Mid 19th century; earliest use found in Nathaniel Hawthorne (1804–1864), author. From September + -ish.