Petaluma Gap — a mountain pass in Sonoma County, California — is a rewarding subject for landscape photographers. The nearest town is Petaluma, about 5.9 km (3.7 mi) away (Petaluma Gap lies WNW of town).
The Petaluma Gap is a geographical region in Sonoma County, California which extends in a band from the Pacific Ocean to San Pablo Bay. It is an area of low land 22 to 31 miles (35 to 50 kilometers) wide in the coast ranges of the northern San Francisco Bay Area. The western edge of the gap is located in the coastal lowlands between Bodega Bay and Tomales Bay. The eastern edge of the gap is located at San Pablo Bay around the mouth of the Petaluma River. The city of Petaluma is near the center of the gap. The Petaluma Gap affects wind patterns (and thus microclimates and air quality) in the San Francisco Bay Area. Fresh marine air generally blows eastward through the gap, branching into southward and northward streams which blow toward the Carquinez Strait and Santa Rosa respectively. The southward stream brings marine air overland into the central Bay Area from the northwest. Warm...From the Wikipedia article “Petaluma Gap”, licensed under CC BY-SA 4.0.
Sunrise & sunset directions
At Petaluma Gap the sunrise point swings a long way through the year: about 59° (ENE) at the June solstice and 120° (ESE) in late December. Sunset moves from 301° (WNW) in June to 240° (WSW) in December, and the midday sun climbs to 75° in summer but only 28° in winter.
| Date | Sunrise | Azimuth | Sunset | Azimuth | Noon sun | Daylight |
|---|---|---|---|---|---|---|
| March equinox (Mar 20) | 7:15 AM | 90° E | 7:23 PM | 271° W | 52° | 12h 08m |
| June solstice (Jun 21) | 5:48 AM | 59° ENE | 8:38 PM | 301° WNW | 75° | 14h 50m |
| September equinox (Sep 22) | 6:59 AM | 89° E | 7:09 PM | 271° W | 52° | 12h 10m |
| December solstice (Dec 21) | 7:25 AM | 120° ESE | 4:55 PM | 240° WSW | 28° | 9h 30m |
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
Mountain passes sit above valleys, so they reward sunrise and sunset with layered ridges, valley fog and long shadows.
| Month (15th) | Blue hour starts | Sunrise | Golden hour ends | Golden hour starts | Sunset | Blue hour ends | Daylight |
|---|---|---|---|---|---|---|---|
| January | 6:58 AM | 7:27 AM | 8:07 AM | 4:35 PM | 5:15 PM | 5:44 PM | 9h 48m |
| February | 6:35 AM | 7:02 AM | 7:39 AM | 5:13 PM | 5:50 PM | 6:17 PM | 10h 48m |
| March | 6:56 AM | 7:23 AM | 7:58 AM | 6:43 PM | 7:18 PM | 7:45 PM | 11h 55m |
| April | 6:08 AM | 6:36 AM | 7:11 AM | 7:12 PM | 7:47 PM | 8:14 PM | 13h 12m |
| May | 5:31 AM | 6:01 AM | 6:38 AM | 7:38 PM | 8:15 PM | 8:45 PM | 14h 15m |
| June | 5:16 AM | 5:48 AM | 6:27 AM | 7:57 PM | 8:37 PM | 9:08 PM | 14h 49m |
| July | 5:29 AM | 6:00 AM | 6:39 AM | 7:56 PM | 8:35 PM | 9:05 PM | 14h 34m |
| August | 5:58 AM | 6:26 AM | 7:03 AM | 7:30 PM | 8:06 PM | 8:34 PM | 13h 40m |
| September | 6:27 AM | 6:53 AM | 7:28 AM | 6:46 PM | 7:21 PM | 7:47 PM | 12h 27m |
| October | 6:54 AM | 7:20 AM | 7:56 AM | 5:58 PM | 6:34 PM | 7:01 PM | 11h 14m |
| November | 6:25 AM | 6:53 AM | 7:32 AM | 4:21 PM | 5:00 PM | 5:28 PM | 10h 07m |
| December | 6:52 AM | 7:21 AM | 8:03 AM | 4:11 PM | 4:52 PM | 5:22 PM | 9h 31m |
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 Petaluma Gap, the Milky Way core is visible in a dark sky from March through September. June gives the longest window (about 5.2 hours on a moonless night), and the core peaks around 23° above the southern horizon. Our light-pollution model puts the sky at about Bortle 6 (bright suburban sky), 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 | — | -1° | — |
| February | 5:09 AM – 5:29 AM | 0.3 | 13° | SE → SE |
| March | 4:16 AM – 5:46 AM | 1.5 | 19° | SE → SSE |
| April | 2:21 AM – 4:51 AM | 2.5 | 22° | SE → S |
| May | 12:22 AM – 4:12 AM | 3.8 | 23° | SE → SSW |
| June | 10:33 PM – 3:43 AM | 5.2 | 23° | SE → SSW |
| July | 10:26 PM – 2:26 AM | 4.0 | 23° | SSE → SW |
| August | 9:44 PM – 12:24 AM | 2.7 | 23° | S → SW |
| September | 8:50 PM – 10:20 PM | 1.5 | 19° | SSW → SW |
| October | 8:02 PM – 8:22 PM | 0.3 | 13° | SW → SW |
| November | Below 10° in darkness | — | 0° | — |
| December | Below 10° in darkness | — | -19° | — |
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: 6 Bortle 6 — Bright suburban sky. The Milky Way is only visible near the zenith; the sky glows grey-orange in photos. Modeled zenith brightness ≈ 19.37 mag/arcsec².
Weather & best season
Long-term NASA satellite data for this area show July as the clearest month (about 19% average cloud cover) and December as the cloudiest (57%). 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 | 73 | 75 | 76 | 87 | 100 | 106 | 109 | 107 | 112 | 103 | 87 | 71 |
| Low °F | 25 | 27 | 28 | 30 | 35 | 42 | 48 | 48 | 45 | 37 | 27 | 24 |
| Precip. (in) | 4.7 | 5.1 | 3.7 | 1.9 | 0.8 | 0.2 | 0.0 | 0.0 | 0.1 | 1.3 | 2.9 | 6.2 |
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 pass
- Check road status before driving: many high passes close seasonally or after storms.
- Look for the road itself as a leading line — switchbacks from above make strong compositions.
- Weather changes fast at elevation; carry layers even in summer.
- Summit pull-outs often face one direction; use the sun azimuth table to see whether sunrise or sunset suits the view.
- Scout in daylight if you plan to shoot at night or before sunrise.
Season: Summer and early autumn are the main season; winter visits depend on plowing and avalanche conditions.
Suggested gear: Telephoto lens, Tripod, Warm layers, Road-condition app. Work out exposures with the depth of field, ND filter and NPF rule calculators.
Nearby photo spots
Other locations within 25 km of Petaluma Gap, closest first.
Lake
Mountain Peak
State Park
State Park
Botanical Garden
State Park
Botanical Garden
State Park
Natural ArchCampgrounds nearby (Recreation.gov)
FAQ
When is the best time to photograph Petaluma Gap?
What time is golden hour at Petaluma Gap?
Where does the sun rise and set at Petaluma Gap?
Can you see the Milky Way from Petaluma Gap?
Do you need a permit to photograph at Petaluma Gap?
How far is Petaluma Gap from Petaluma?
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.