Overview
- The autumnal equinox occurred Tuesday at 8:05 p.m. Eastern, the precise instant the Sun’s center crossed Earth’s equator and astronomers mark the start of astronomical fall.
- Observers should not expect exactly 12 hours of daylight on that date because sunrise and sunset are defined by the Sun’s upper edge and the atmosphere bends sunlight, which delays the local equilux by days depending on latitude.
- Local equilux dates vary widely, with Maine’s equilux happening around Sept. 25 and much of the mid‑Atlantic near Sept. 27, so residents can use zip‑code daylight tools and equilux maps to find their nearest date.
- NOAA data show most U.S. locations will lose roughly 3 to 3.5 hours of daylight between the equinox and the winter solstice, a change that triggers leaf color shifts as trees reduce chlorophyll production.
- Skywatchers have a near‑term highlight when the Harvest Moon peaks around Sept. 26, and communities from London to U.S. parks are holding equinox events while forecasters note a strengthening El Niño could influence fall weather.