An equinox is the precise time twice a year when the sun shines directly above the earth's equator, resulting in nearly equal amounts of day and night. [1, 2] Key Facts About the Fall Equinox When it happens: Twice a year around March 20 (spring) and September 22 (autumn). The 2026 autumn equinox: Arrives on September 22, 2026, at 5:05 p.m. PDT (00:05 UTC on Sept. 23). Meaning of the name: Comes from Latin words aequus (equal) and nox (night). Day vs. night length: Days are a
