What time does it get dark in Boulder, CO?
In Boulder, sunset ranges from about 4:37 PM around December 8 to about 8:35 PM around June 27. The shortest day (December 22) has 9h 19m of daylight and the longest (June 21) has 15h 01m. When daylight saving time ends on Sunday, November 1, 2026, sunset jumps from about 6:01 PM to 5:00 PM overnight.
Working out today's sunset…
Sunset and last light in Boulder, month by month
Times for the 15th of each month in 2026, local time. "Start by" is the latest start for a 30 or 60 minute run, ride or walk that finishes by sunset. Last light is when civil twilight ends and it becomes too dark to see without a light.
| Month | Sunrise | Sunset | Last light | Daylight | 30-min start by | 60-min start by |
|---|---|---|---|---|---|---|
| January | 7:22 AM | 5:00 PM | 5:30 PM | 9h 39m | 4:30 PM | 4:00 PM |
| February | 6:55 AM | 5:37 PM | 6:05 PM | 10h 42m | 5:07 PM | 4:37 PM |
| March | 7:13 AM | 7:08 PM | 7:35 PM | 11h 55m | 6:38 PM | 6:08 PM |
| April | 6:24 AM | 7:40 PM | 8:08 PM | 13h 16m | 7:10 PM | 6:40 PM |
| May | 5:47 AM | 8:10 PM | 8:41 PM | 14h 23m | 7:40 PM | 7:10 PM |
| June | 5:32 AM | 8:32 PM | 9:05 PM | 15h 00m | 8:02 PM | 7:32 PM |
| July | 5:45 AM | 8:30 PM | 9:02 PM | 14h 44m | 8:00 PM | 7:30 PM |
| August | 6:14 AM | 7:59 PM | 8:28 PM | 13h 46m | 7:29 PM | 6:59 PM |
| September | 6:43 AM | 7:12 PM | 7:39 PM | 12h 29m | 6:42 PM | 6:12 PM |
| October | 7:12 AM | 6:23 PM | 6:50 PM | 11h 11m | 5:53 PM | 5:23 PM |
| November | 6:47 AM | 4:46 PM | 5:15 PM | 9h 59m | 4:16 PM | 3:46 PM |
| December | 7:17 AM | 4:38 PM | 5:08 PM | 9h 21m | 4:08 PM | 3:38 PM |
Heading out near dark in Boulder
From late fall through winter it is dark in Boulder before 6 p.m., so after-work runs and walks happen in the dark for months. If you head out close to sunset, be seen and be findable: wear a light and something reflective on the parts of you that move, pick a route with streetlights and other people, and send someone a live location link with a return time before you go. Our guide to running in the dark after the clocks change covers the rest.
Questions people ask
What time does it get dark in Boulder in winter?
In mid-December the sun sets around 4:38 PM in Boulder and last light (the end of civil twilight) is around 5:08 PM. The earliest sunset of 2026 is about 4:37 PM, around December 8.
When is the latest sunset in Boulder?
The latest sunset of 2026 in Boulder is about 8:35 PM, around June 27. In mid-June, usable light lasts until roughly 9:05 PM.
How much earlier does it get dark in Boulder after daylight saving time ends?
Daylight saving time ends on Sunday, November 1, 2026. Sunset in Boulder moves from about 6:01 PM on October 31 to about 5:00 PM on November 1, so an after-work run that finished in daylight the week before can finish in the dark.
What time should I start a run in Boulder to finish before dark?
Subtract your run time from sunset. A 60-minute run in Boulder should start by about 3:38 PM in mid-December and by about 7:32 PM in mid-June. The table on this page lists the latest start for 30 and 60 minute runs in every month, and the calculator at the top gives today's times.
Keep reading
Calculated from Boulder's coordinates (40.01, -105.27) with the standard solar position formulas used by NOAA. Times can differ by a minute or two from other sources, and hills or buildings bring darkness sooner.