Weather
Billings Fall Begins at 6:05 PM With 12-Hour Day
Billings, Montana – Fall officially begins at 6:05 p.m. Tuesday in Billings, which will still receive 12 hours and 10 minutes of daylight on the equinox.
By Cameron Hayes · 2026-09-22T09:06:09.551Z
Billings, Montana – Fall officially begins at 6:05 p.m. Tuesday in Billings, which will still receive 12 hours and 10 minutes of daylight on the equinox.
According to the National Weather Service in Billings, the autumnal equinox marks the beginning of astronomical fall, when the sun's rays fall directly on the equator and day and night are roughly equal.
But “equinox” does not mean Billings receives exactly 12 hours of daylight Tuesday.
The Weather Service said the day when daylight and darkness become equal in southern Montana arrives Friday. That difference helps explain why Billings still gets 12 hours and 10 minutes of daylight on the first day of astronomical fall.
The apparent mismatch stems in part from how sunrise and sunset are defined. Sunrise occurs when the upper edge of the sun first appears above the horizon, while sunset is recorded when that edge disappears. Atmospheric refraction also makes the sun appear above the horizon when it is physically slightly below it, adding daylight around sunrise and sunset.
Tuesday's equinox is nevertheless an important turning point. From here, daylight will continue decreasing across Montana as the Northern Hemisphere moves toward the winter solstice and its shortest days of the year.
Astronomical fall is different from meteorological, or climatological, fall, which began Sept. 1 and divides the seasons into three month periods for weather and climate records.
For Billings, astronomical autumn starts precisely at 6:05 p.m. Tuesday. Residents looking for the closest thing to an equal 12 hour split between daylight and darkness will have to wait until Friday.