Sunset Forecast for O'Fallon

For the most colorful sunsets, look for days with scattered mid-level clouds, which catch and reflect warm light. Head to a location with a clear view of the western horizon such as a beach, hilltop, or open field. Arrive during golden hour, about an hour before sunset, for the best light. Use Alpenglow's quality forecast to find the days when conditions favor vivid colors.

Today's sunset in O'Fallon is at 8:24 PM, with full darkness arriving at 10:21 PM (America/Chicago). The period between sunset and full darkness is twilight, when the sky gradually transitions from light to dark.

Twilight typically lasts between 70 and 100 minutes from sunset to full darkness. It consists of three phases: civil twilight (brightest, about 30 minutes), nautical twilight (medium, about 30 minutes), and astronomical twilight (dimmest, about 30 minutes). The exact duration depends on latitude and the time of year — twilight is longer at higher latitudes and around the solstices.

The latest sunset in O'Fallon in 2026 is at 8:29 PM on June 24 (America/Chicago). This occurs shortly after the summer solstice.

After sunset at 8:24 PM in O'Fallon, civil twilight ends at 8:56 PM — about 32 minutes later. Full darkness (astronomical dusk) arrives at 10:21 PM (America/Chicago).