Located in Washington County, Oregon, Cooper Mountain is a mountain peak at about 237 m (778 ft) above sea level. The nearest town is Aloha, about 4.4 km (2.7 mi) away (Cooper Mountain lies S of town).
Cooper Mountain is a summit in Washington County, Oregon, United States. Its summit has an elevation of 764 feet (233 m). The mountain and surrounding area are named for Ohio immigrant Perry Cooper who settled on the mountain.From the Wikipedia article “Cooper Mountain (Oregon)”, licensed under CC BY-SA 4.0.
Sunrise & sunset directions
At Cooper Mountain the sunrise point swings a long way through the year: about 55° (NE) at the June solstice and 124° (ESE) in late December. Sunset moves from 306° (NW) in June to 237° (WSW) in December, and the midday sun climbs to 68° in summer but only 21° in winter.
| Date | Sunrise | Azimuth | Sunset | Azimuth | Noon sun | Daylight |
|---|---|---|---|---|---|---|
| March equinox (Mar 20) | 7:15 AM | 89° E | 7:24 PM | 271° W | 44° | 12h 09m |
| June solstice (Jun 21) | 5:24 AM | 55° NE | 9:04 PM | 306° NW | 68° | 15h 41m |
| September equinox (Sep 22) | 6:59 AM | 89° E | 7:11 PM | 271° W | 45° | 12h 12m |
| December solstice (Dec 21) | 7:49 AM | 124° ESE | 4:32 PM | 237° WSW | 21° | 8h 42m |
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
Summits catch first and last light — alpenglow can turn rock pink or orange minutes before sunrise and after sunset while valleys stay in shadow.
| Month (15th) | Blue hour starts | Sunrise | Golden hour ends | Golden hour starts | Sunset | Blue hour ends | Daylight |
|---|---|---|---|---|---|---|---|
| January | 7:15 AM | 7:48 AM | 8:35 AM | 4:08 PM | 4:55 PM | 5:28 PM | 9h 07m |
| February | 6:44 AM | 7:14 AM | 7:56 AM | 4:57 PM | 5:39 PM | 6:09 PM | 10h 25m |
| March | 6:55 AM | 7:25 AM | 8:04 AM | 6:38 PM | 7:18 PM | 7:47 PM | 11h 53m |
| April | 5:56 AM | 6:27 AM | 7:06 AM | 7:18 PM | 7:58 PM | 8:28 PM | 13h 31m |
| May | 5:07 AM | 5:42 AM | 6:25 AM | 7:53 PM | 8:36 PM | 9:10 PM | 14h 54m |
| June | 4:45 AM | 5:23 AM | 6:09 AM | 8:17 PM | 9:02 PM | 9:40 PM | 15h 39m |
| July | 5:02 AM | 5:38 AM | 6:23 AM | 8:14 PM | 8:58 PM | 9:34 PM | 15h 20m |
| August | 5:41 AM | 6:13 AM | 6:54 AM | 7:40 PM | 8:21 PM | 8:53 PM | 14h 07m |
| September | 6:21 AM | 6:51 AM | 7:30 AM | 6:45 PM | 7:24 PM | 7:54 PM | 12h 34m |
| October | 6:58 AM | 7:28 AM | 8:09 AM | 5:47 PM | 6:27 PM | 6:57 PM | 10h 59m |
| November | 6:39 AM | 7:11 AM | 7:56 AM | 3:58 PM | 4:43 PM | 5:15 PM | 9h 31m |
| December | 7:11 AM | 7:45 AM | 8:35 AM | 3:40 PM | 4:30 PM | 5:04 PM | 8h 44m |
Local time (America/Los Angeles), 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 Cooper Mountain, the Milky Way core is visible in a dark sky from April through August. June gives the longest window (about 3.0 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 7 (suburban / urban transition), so expect visible sky glow; drive away from towns for better results.
| Month | Core visible (15th) | Hours | Max altitude | Direction |
|---|---|---|---|---|
| January | Below 10° in darkness | — | -4° | — |
| February | Below 10° in darkness | — | 7° | — |
| March | 5:16 AM – 5:36 AM | 0.3 | 12° | SSE → SSE |
| April | 3:16 AM – 4:26 AM | 1.2 | 15° | SSE → SSE |
| May | 1:16 AM – 3:26 AM | 2.2 | 16° | SSE → S |
| June | 11:39 PM – 2:39 AM | 3.0 | 16° | SSE → SSW |
| July | 11:22 PM – 1:22 AM | 2.0 | 16° | S → SSW |
| August | 10:17 PM – 11:27 PM | 1.2 | 14° | SSW → SSW |
| September | 9:06 PM – 9:26 PM | 0.3 | 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: 7 Bortle 7 — Suburban / urban transition. The whole sky has a grey-white glow; the Milky Way is invisible to the eye. Modeled zenith brightness ≈ 18.61 mag/arcsec². Aurora needs roughly Kp 6.0+ 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 39% average cloud cover) and December as the cloudiest (80%). August is the warmest month and December 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 | 62 | 66 | 74 | 84 | 93 | 100 | 105 | 104 | 101 | 87 | 67 | 61 |
| Low °F | 8 | 15 | 22 | 27 | 33 | 39 | 45 | 44 | 36 | 24 | 15 | 10 |
| Precip. (in) | 8.4 | 6.1 | 6.8 | 4.8 | 3.1 | 2.2 | 0.4 | 0.7 | 2.3 | 5.3 | 8.6 | 9.7 |
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 mountain peak
- Afternoon thunderstorms are common in summer at high elevations — plan summit hikes for early morning.
- Snow on the summit holds detail best when you expose for the highlights and lift shadows later.
- Alpenglow lasts only a few minutes; set up and focus beforehand.
- Clouds around the summit add drama — a clear blue sky is often the least interesting condition.
- Bring a spare battery — cold weather and long exposures drain them fast.
Season: Early summer keeps snow on the peaks with green valleys below; autumn adds aspen or larch color in many ranges.
Suggested gear: Telephoto lens, Lightweight tripod, Warm layers, Microspikes in shoulder seasons. Work out exposures with the depth of field, ND filter and NPF rule calculators.
Nearby photo spots
Other locations within 25 km of Cooper Mountain, closest first.
National Wildlife Refuge
Mountain Peak
Botanical Garden
State Park
State Park
Botanical Garden
Botanical Garden
BeachBeachFAQ
When is the best time to photograph Cooper Mountain?
What time is golden hour at Cooper Mountain?
Where does the sun rise and set at Cooper Mountain?
Can you see the Milky Way from Cooper Mountain?
Do you need a permit to photograph at Cooper Mountain?
How far is Cooper Mountain from Aloha?
Sources
Location data: Wikidata, USGS GNIS / GeoNames, 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.