Boulder, CO · 2026
Sunrise and sunset in Boulder, Colorado
Short answer
- Longest day
- 15 h 01 min
- Shortest day
- 9 h 20 min
Boulder daylight through 2026
Daylight in Boulder runs from 9 h 20 min on December 21 to 15 h 01 min on June 21, a seasonal swing of 5 h 42 min between June 21 and December 21. That swing ranks 88th of 342 US cities of 100,000+, where 1st is the largest. Around the March equinox the city gets 12 h 09 min, and around the September equinox 12 h 09 min.
Boulder daylight by month
| Month | Average | Sunrise | Sunset |
|---|---|---|---|
| January | 9 h 43 min | 7:10 AM to 7:23 AM | 4:46 PM to 5:19 PM |
| February | 10 h 43 min | 6:35 AM to 7:09 AM | 5:20 PM to 5:51 PM |
| March | 11 h 58 min | 6:24 AM to 7:23 AM | 5:53 PM to 7:24 PM |
| April | 13 h 18 min | 6:02 AM to 6:44 AM | 7:25 PM to 7:54 PM |
| May | 14 h 25 min | 5:34 AM to 6:00 AM | 7:55 PM to 8:23 PM |
| June | 14 h 58 min | 5:31 AM to 5:35 AM | 8:24 PM to 8:34 PM |
| July | 14 h 41 min | 5:35 AM to 5:58 AM | 8:15 PM to 8:33 PM |
| August | 13 h 42 min | 5:59 AM to 6:27 AM | 7:33 PM to 8:14 PM |
| September | 12 h 26 min | 6:28 AM to 6:56 AM | 6:44 PM to 7:32 PM |
| October | 11 h 07 min | 6:57 AM to 7:29 AM | 5:59 PM to 6:43 PM |
| November | 9 h 58 min | 6:30 AM to 7:02 AM | 4:36 PM to 4:58 PM |
| December | 9 h 23 min | 7:03 AM to 7:22 AM | 4:35 PM to 4:45 PM |
Earliest sunrise, latest sunset and the clock
The earliest sunrise comes on June 9 at 5:31 AM and the latest sunset on June 25 at 8:34 PM. The latest sunrise is 7:29 AM on October 31. Daylight saving time starts and ends on March 8 and November 1, which shifts every clock time by an hour.
On standard time the clocks run 7 hours behind UTC, the time of the 105° W meridian. Boulder sits at 105.25° W, so the sun runs about 1 minutes behind the zone clock. Solar noon is at 12:10 PM on January 15 and 1:07 PM on July 15.
Compared with nearby cities
Denver, the state capital, gets 2 minutes less daylight than Boulder on June 21 and 2 minutes more on December 21. Day length depends on latitude, so the table lists the paired cities from north to south.
| City | Latitude | June 21 | December 21 |
|---|---|---|---|
| Fort Collins, CO | 40.55° N | 15 h 05 min | 9 h 16 min |
| Greeley, CO | 40.42° N | 15 h 04 min | 9 h 17 min |
| Provo, UT | 40.25° N | 15 h 03 min | 9 h 18 min |
| Boulder, CO | 40.02° N | 15 h 01 min | 9 h 20 min |
| Thornton, CO | 39.92° N | 15 h 00 min | 9 h 20 min |
| Westminster, CO | 39.88° N | 15 h 00 min | 9 h 20 min |
| Arvada, CO | 39.83° N | 15 h 00 min | 9 h 21 min |
| Denver, CO | 39.76° N | 14 h 59 min | 9 h 21 min |
| Aurora, CO | 39.71° N | 14 h 59 min | 9 h 21 min |
| Lakewood, CO | 39.70° N | 14 h 59 min | 9 h 22 min |
| Centennial, CO | 39.59° N | 14 h 58 min | 9 h 22 min |
Questions people ask
What is the longest day of the year in Boulder?
June 21, 2026, with 15 h 01 min of daylight: sunrise 5:32 AM, sunset 8:33 PM.
What is the shortest day in Boulder?
December 21, 2026, with 9 h 20 min: sunrise 7:19 AM, sunset 4:38 PM.
When is the latest sunset in Boulder?
8:34 PM on June 25, 2026. The earliest sunset is 4:35 PM on December 2.
What time zone is Boulder in?
America/Denver. Clocks change on March 8 (to MDT) and November 1 (to MST) in 2026.
Sources and data as of
Data as of: computed for 2026 at the Census internal point of Boulder, 40.024° N, 105.251° W; time zone from Open-Meteo.
- 01SunCalc library (Vladimir Agafonkin), algorithms after Jean Meeus
- 02IANA time zone database (clock times and daylight saving rules)
How every number is computed: methodology. Spotted a wrong figure? Report an error.