The seventh month of the Shire Calendar, following, as its name suggests, the Midsummer feast days of Lithe, and followed in turn by the month of Wedmath. Afterlithe was approximately equivalent to modern July; specifically, it ran from modern 24 June to 23 July in a normal year.
The use of the name 'Afterlithe' was local to the Shire-hobbits; even the closely related calendar of Bree used a different name for this month, which they called 'Mede'.