Sunrise and Sunset times in Boulder, United States 
Boulder
Colorado
Time zone: America/Denver, UTC -6 h.
Latitude: 40.0249, Longitude: -105.252
126 054 people
| Date | Sunrise | Solar Noon | Sunset | Length of day |
|---|---|---|---|---|
| 2025-Jul-01, Tuesday | 05:36:07 | 13:05:01 | 20:33:54 | 14h 57m 47s |
| 2025-Jul-02, Wednesday | 05:36:38 | 13:05:12 | 20:33:45 | 14h 57m 7s |
| 2025-Jul-03, Thursday | 05:37:11 | 13:05:23 | 20:33:35 | 14h 56m 24s |
| 2025-Jul-04, Friday | 05:37:44 | 13:05:33 | 20:33:22 | 14h 55m 38s |
| 2025-Jul-05, Saturday | 05:38:20 | 13:05:44 | 20:33:08 | 14h 54m 48s |
| 2025-Jul-06, Sunday | 05:38:56 | 13:05:54 | 20:32:51 | 14h 53m 55s |
| 2025-Jul-07, Monday | 05:39:33 | 13:06:03 | 20:32:33 | 14h 53m 0s |
| 2025-Jul-08, Tuesday | 05:40:12 | 13:06:12 | 20:32:12 | 14h 52m 0s |
| 2025-Jul-09, Wednesday | 05:40:52 | 13:06:21 | 20:31:50 | 14h 50m 58s |
| 2025-Jul-10, Thursday | 05:41:33 | 13:06:29 | 20:31:26 | 14h 49m 53s |
| 2025-Jul-11, Friday | 05:42:15 | 13:06:37 | 20:30:59 | 14h 48m 44s |
| 2025-Jul-12, Saturday | 05:42:59 | 13:06:45 | 20:30:31 | 14h 47m 32s |
| 2025-Jul-13, Sunday | 05:43:43 | 13:06:52 | 20:30:01 | 14h 46m 18s |
| 2025-Jul-14, Monday | 05:44:28 | 13:06:58 | 20:29:29 | 14h 45m 1s |
| 2025-Jul-15, Tuesday | 05:45:14 | 13:07:04 | 20:28:55 | 14h 43m 41s |
| 2025-Jul-16, Wednesday | 05:46:01 | 13:07:10 | 20:28:19 | 14h 42m 18s |
| 2025-Jul-17, Thursday | 05:46:48 | 13:07:15 | 20:27:41 | 14h 40m 53s |
| 2025-Jul-18, Friday | 05:47:37 | 13:07:19 | 20:27:01 | 14h 39m 24s |
| 2025-Jul-19, Saturday | 05:48:26 | 13:07:23 | 20:26:20 | 14h 37m 54s |
| 2025-Jul-20, Sunday | 05:49:16 | 13:07:26 | 20:25:36 | 14h 36m 20s |
| 2025-Jul-21, Monday | 05:50:06 | 13:07:29 | 20:24:51 | 14h 34m 45s |
| 2025-Jul-22, Tuesday | 05:50:58 | 13:07:31 | 20:24:04 | 14h 33m 6s |
| 2025-Jul-23, Wednesday | 05:51:49 | 13:07:32 | 20:23:16 | 14h 31m 27s |
| 2025-Jul-24, Thursday | 05:52:42 | 13:07:33 | 20:22:25 | 14h 29m 43s |
| 2025-Jul-25, Friday | 05:53:34 | 13:07:34 | 20:21:33 | 14h 27m 59s |
| 2025-Jul-26, Saturday | 05:54:28 | 13:07:34 | 20:20:39 | 14h 26m 11s |
| 2025-Jul-27, Sunday | 05:55:21 | 13:07:33 | 20:19:44 | 14h 24m 23s |
| 2025-Jul-28, Monday | 05:56:16 | 13:07:31 | 20:18:47 | 14h 22m 31s |
| 2025-Jul-29, Tuesday | 05:57:10 | 13:07:29 | 20:17:48 | 14h 20m 38s |
| 2025-Jul-30, Wednesday | 05:58:05 | 13:07:27 | 20:16:48 | 14h 18m 43s |
| 2025-Jul-31, Thursday | 05:59:00 | 13:07:23 | 20:15:46 | 14h 16m 46s |
Boulder on United States map:
Cities in the same time zone America/Denver
Denver (Colorado), Salt Lake City (Utah), El Paso (Texas), Albuquerque (New Mexico), Colorado Springs (Colorado), Ogden (Utah), Provo (Utah), Aurora (Colorado), Fort Collins (Colorado), Lakewood (Colorado), Pueblo (Colorado), Thornton (Colorado), Grand Junction (Colorado), West Valley City (Utah), Las Cruces (New Mexico), Greeley (Colorado), Billings (Montana), Arvada (Colorado), St. George (Utah), West Jordan (Utah), Westminster (Colorado), Centennial (Colorado), Santa Fe (New Mexico), Highlands Ranch (Colorado), Logan (Utah), Longmont (Colorado), Orem (Utah), Rio Rancho (New Mexico), Sandy (Utah), Lafayette (Colorado)
Largest Populated Areas in United States
New York (New York), Los Angeles (California), Chicago (Illinois), Miami (Florida), Dallas (Texas), Philadelphia (Pennsylvania), Houston (Texas), Washington (District of Columbia), Atlanta (Georgia), Boston (Massachusetts), Phoenix (Arizona), Seattle (Washington), San Francisco (California), Detroit (Michigan), San Diego (California), Minneapolis (Minnesota), Tampa (Florida), Denver (Colorado), Brooklyn (New York), Queens (New York), Baltimore (Maryland), Riverside (California), St. Louis (Missouri), Las Vegas (Nevada), Portland (Oregon), San Antonio (Texas), Sacramento (California), San Jose (California), Orlando (Florida), Cleveland (Ohio)
Daylight Hours FAQ: 10 Most Googled Questions Answered
1. What are daylight hours?
Daylight hours refer to the period between sunrise and sunset. This duration changes throughout the year based on season and geographic location.
2. Why are days shorter in winter and longer in summer?
Earth's 23.5° axial tilt causes uneven sunlight distribution. Your hemisphere receives less direct sunlight in winter (shorter days) and more in summer (longer days).
3. When is the longest day of the year?
Northern Hemisphere: June 20-22 (summer solstice).
Southern Hemisphere: December 21-23.
Near polar circles, the sun doesn't set for 24 hours.
4. When is the shortest day of the year?
Northern Hemisphere: December 21-22 (winter solstice).
Southern Hemisphere: June 20-21.
5. How does latitude affect daylight hours?
The closer to poles, the more extreme variations:
- Equator: ~12-hour days year-round
- Polar regions: Midnight sun/polar nights occur
6. Why do New York and Miami have different day lengths?
Miami's lower latitude means:
- Winter days are longer than NY's
- Summer days are slightly shorter
7. When are day and night equal?
During equinoxes:
- Spring: March 20-21
- Fall: September 22-23
How fast do days lengthen/shorten?
Most rapid change near equinoxes: 2-4 minutes daily.
Slowest change near solstices: <1 minute daily.
9. Where can I check daylight hours for my city?
Reliable tools:
- Timeanddate.com
- SunCalc.org
- Photographer's Ephemeris app
10. Does daylight affect health?
Yes. Reduced winter sunlight may cause:
- Seasonal Affective Disorder (SAD)
- Vitamin D deficiency
Solution: Light therapy lamps & midday walks