Casper, WY: shortest day and earliest sunset
The shortest day in Casper
On Dec 21 the sun rises at 7:33 am and sets at 4:34 pm: 9h 01m of daylight, a moderate winter. The longest day of summer has 15h 21m, so the swing is 6h 19m.
When it gets better in Casper
- Earliest sunset: 4:31 pm on Dec 8, before the shortest day (here is why).
- Latest sunrise (standard time): 7:36 am on Jan 3.
- Back above 10 hours of daylight: Feb 2.
- By Feb 21 the days grow by 2.8 minutes a day.
Waking and coming home in the dark
With a 7:00 am alarm, the sun is not yet up on 97 weekdays a year. Heading home at 5:30 pm, it has already set on 72. 60 weekdays start and end in the dark. The alarm and lamp guide shows how that compares across the country.
At 42.8°N this sits between Sarasota FL (27°N, 1.4%) and Nashua NH (43°N, 9.7%) in a 1990 survey of winter depression by latitude.
What to do about it in Casper
- A sunrise alarm clock is worth considering if you get up at 7:00 am or earlier: 52 weekday mornings here are still properly dark at that hour, mostly between Sep 29 and Mar 24.
- On daylight grounds there is a strong case for a light therapy lamp: 60 weekdays start and end in the dark. Use it in the morning, and if winter low mood is the reason, ask a doctor before you rely on one.
- If you head home at 5:30 pm, the sun has already set from Nov 2 to Feb 9: worth checking your bike lights and porch light before Nov 2.
Daylight in Casper, month by month
Sunrise, sunset and day length on the 21st of each month, local clock time. December is the darkest, at 9h 01m.
| Month | Sunrise | Sunset | Daylight |
|---|---|---|---|
| July 2026 | 5:46 am | 8:37 pm | 14h 51m |
| August 2026 | 6:18 am | 7:58 pm | 13h 40m |
| September 2026 | 6:52 am | 7:04 pm | 12h 12m |
| October 2026 | 7:26 am | 6:13 pm | 10h 47m |
| November 2026 | 7:05 am | 4:37 pm | 9h 32m |
| December 2026 | 7:33 am | 4:34 pm | 9h 01m |
| January 2027 | 7:30 am | 5:04 pm | 9h 34m |
| February 2027 | 6:54 am | 5:45 pm | 10h 51m |
| March 2027 | 7:07 am | 7:19 pm | 12h 12m |
| April 2027 | 6:14 am | 7:54 pm | 13h 40m |
| May 2027 | 5:37 am | 8:27 pm | 14h 51m |
| June 2027 | 5:27 am | 8:47 pm | 15h 21m |
Casper against the places around it
On the shortest day, compared with Casper (9h 01m, sunset 4:34 pm):
- Riverton, WY, 105 mi away: 9h 00m of daylight (-1 min), sunset 4:42 pm (+8 min).
- Gillette, WY, 107 mi away: 8h 51m of daylight (-10 min), sunset 4:26 pm (-8 min).
- Laramie, WY, 112 mi away: 9h 11m of daylight (+10 min), sunset 4:36 pm (+2 min).
- Sheridan, WY, 139 mi away: 8h 47m of daylight (-14 min), sunset 4:30 pm (-4 min).
- Cheyenne, WY, 142 mi away: 9h 13m of daylight (+12 min), sunset 4:34 pm (0 min).