Originally a pictograph of a cricket, since cricket chirps indicate the beginning of autumn. Later the character was reanalyzed as 禾 (grain) + 火 (fire).
Shuowen Jiezi
《說文》：“秋，禾穀孰也。从禾，省聲。，籀文不省。”
Components
禾(iconic) — Autumn is the season for harvesting grain.