Upper Sioux Agency State Park is a state park in Yellow Medicine County, Minnesota. It sits roughly 10.9 km (6.8 mi) SE of Granite Falls. It is listed on the National Register of Historic Places.
Upper Sioux Agency (or Yellow Medicine Agency), was a federal administrative center in Minnesota established in response to treaties with the Dakota people in what became Yellow Medicine County. Located on the Minnesota River south of Granite Falls, Minnesota, the government-run campus of employee housing, warehouses and a manual labor school was destroyed in the Dakota War of 1862. The grave of Chief Walking Iron Mazomani, a leader of the Wahpetonwan (Dwellers in the Leaves) Dakota tribes, who was killed during the 1862 Dakota War's Battle of Wood Lake, is here. The site was listed on the National Register of Historic Places in 1970 for having state-level significance under the themes of archaeology, architecture, education, and social history.From the Wikipedia article “Upper Sioux Agency”, licensed under CC BY-SA 4.0.
Sunrise & sunset directions
At Upper Sioux Agency State Park the sunrise point swings a long way through the year: about 55° (NE) at the June solstice and 123° (ESE) in late December. Sunset moves from 305° (NW) in June to 237° (WSW) in December, and the midday sun climbs to 69° in summer but only 22° in winter.
| Date | Sunrise | Azimuth | Sunset | Azimuth | Noon sun | Daylight |
|---|---|---|---|---|---|---|
| March equinox (Mar 20) | 7:26 AM | 90° E | 7:34 PM | 271° W | 45° | 12h 08m |
| June solstice (Jun 21) | 5:37 AM | 55° NE | 9:12 PM | 305° NW | 69° | 15h 35m |
| September equinox (Sep 22) | 7:10 AM | 89° E | 7:21 PM | 271° W | 46° | 12h 12m |
| December solstice (Dec 21) | 7:57 AM | 123° ESE | 4:45 PM | 237° WSW | 22° | 8h 48m |
Azimuth is measured clockwise from true north (90° = east, 270° = west). Computed for 2026; values change by less than a degree from year to year.
Golden hour & blue hour by month
State parks often protect a signature feature — a gorge, lake or overlook — that is best in early morning before visitors and harsh light arrive.
| Month (15th) | Blue hour starts | Sunrise | Golden hour ends | Golden hour starts | Sunset | Blue hour ends | Daylight |
|---|---|---|---|---|---|---|---|
| January | 7:24 AM | 7:56 AM | 8:43 AM | 4:21 PM | 5:07 PM | 5:40 PM | 9h 11m |
| February | 6:53 AM | 7:23 AM | 8:04 AM | 5:09 PM | 5:51 PM | 6:21 PM | 10h 27m |
| March | 7:06 AM | 7:35 AM | 8:14 AM | 6:49 PM | 7:28 PM | 7:57 PM | 11h 53m |
| April | 6:08 AM | 6:38 AM | 7:17 AM | 7:27 PM | 8:07 PM | 8:37 PM | 13h 29m |
| May | 5:21 AM | 5:55 AM | 6:37 AM | 8:01 PM | 8:44 PM | 9:18 PM | 14h 49m |
| June | 4:59 AM | 5:36 AM | 6:21 AM | 8:25 PM | 9:10 PM | 9:47 PM | 15h 34m |
| July | 5:15 AM | 5:51 AM | 6:35 AM | 8:22 PM | 9:06 PM | 9:41 PM | 15h 15m |
| August | 5:53 AM | 6:25 AM | 7:05 AM | 7:49 PM | 8:30 PM | 9:01 PM | 14h 05m |
| September | 6:32 AM | 7:01 AM | 7:40 AM | 6:56 PM | 7:35 PM | 8:04 PM | 12h 33m |
| October | 7:08 AM | 7:38 AM | 8:18 AM | 5:59 PM | 6:39 PM | 7:08 PM | 11h 01m |
| November | 6:48 AM | 7:20 AM | 8:04 AM | 4:11 PM | 4:55 PM | 5:27 PM | 9h 36m |
| December | 7:20 AM | 7:53 AM | 8:41 AM | 3:54 PM | 4:43 PM | 5:16 PM | 8h 49m |
Local time (America/Chicago), including daylight saving time. Golden hour runs from about −4° to +6° solar altitude, so the morning golden hour begins during blue hour, before sunrise.
Milky Way & night sky
From Upper Sioux Agency State Park, the Milky Way core is visible in a dark sky from April through September. June gives the longest window (about 3.3 hours on a moonless night), and the core peaks around 16° above the southern horizon. Our light-pollution model puts the sky at about Bortle 2 (typical truly dark site), which is excellent for astrophotography.
| Month | Core visible (15th) | Hours | Max altitude | Direction |
|---|---|---|---|---|
| January | Below 10° in darkness | — | -4° | — |
| February | Below 10° in darkness | — | 7° | — |
| March | 5:26 AM – 5:46 AM | 0.3 | 12° | SSE → SSE |
| April | 3:24 AM – 4:44 AM | 1.3 | 16° | SSE → S |
| May | 1:21 AM – 3:41 AM | 2.3 | 16° | SSE → S |
| June | 11:40 PM – 3:00 AM | 3.3 | 16° | SSE → SSW |
| July | 11:25 PM – 1:45 AM | 2.3 | 16° | S → SSW |
| August | 10:24 PM – 11:44 PM | 1.3 | 15° | SSW → SSW |
| September | 9:15 PM – 9:45 PM | 0.5 | 12° | SSW → SSW |
| October | Below 10° in darkness | — | 7° | — |
| November | Below 10° in darkness | — | -3° | — |
| December | Below 10° in darkness | — | -20° | — |
Window when the galactic core is at least 10° high during astronomical darkness on the 15th of each month. Pick nights within a few days of the new moon. Plan exact nights with the Milky Way planner.
Estimated sky darkness: 2 Bortle 2 — Typical truly dark site. The summer Milky Way shows rich structure; clouds look like black holes in the stars. Modeled zenith brightness ≈ 21.73 mag/arcsec². Aurora needs roughly Kp 4.5+ to show low on the northern horizon here.
Weather & best season
Long-term NASA satellite data for this area show July as the clearest month (about 44% average cloud cover) and March as the cloudiest (67%). July is the warmest month and January the coldest, which matters for gear, snow access and how long batteries last at night.
Average cloud cover (%)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| High °F | 51 | 67 | 82 | 90 | 94 | 99 | 105 | 101 | 97 | 86 | 77 | 55 |
| Low °F | -39 | -21 | -21 | 6 | 24 | 42 | 48 | 42 | 33 | 11 | -4 | -22 |
| Precip. (in) | 0.6 | 0.8 | 1.4 | 2.8 | 3.5 | 4.3 | 3.0 | 3.4 | 3.1 | 2.3 | 1.0 | 1.1 |
Monthly climatology for the surrounding 1° grid cell from NASA POWER (MERRA-2). Mountain sites can be colder and cloudier than the cell average.
Photography tips for this state park
- Trail maps often mark overlooks — combine them with the sun azimuth to plan.
- Day-use fees or passes are common; buy them online before arriving.
- Check park hours: many state parks close at dusk, which affects sunset and night shooting.
- Ask rangers about photography permits for commercial work, models or drones.
- Weekday mornings are the least crowded at popular viewpoints.
- Bring a spare battery — cold weather and long exposures drain them fast.
Season: Spring wildflowers and autumn color are peak seasons in most parks.
Suggested gear: Versatile zoom lens, Tripod, Park pass. Work out exposures with the depth of field, ND filter and NPF rule calculators.
Permits, drones & access
Drones: Drone rules in state parks vary by state and even by park — many require a permit or ban recreational drone flights. Check the park's rules and the FAA B4UFLY app before flying.
Nearby photo spots
Other locations within 40 km of Upper Sioux Agency State Park, closest first.
Waterfall
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Sources
Location data: Wikidata, Wikipedia. Sun, moon and Milky Way times are computed by LWPhoto Atlas for 2026. Climate: NASA POWER. Sky darkness is a population-based estimate (Walker's law), not a measurement. See data sources & licenses.