SunreachExplainers · Updated
Golden hour in the mountains: when the low sun actually reaches you
Golden hour is the time when the sun is between 4° below and 6° above the horizon, but in the mountains its light reaches you only if the skyline in the sun's direction is lower than 6°. In 2027, low warm light reaches Bovec on 92 evenings and 18 mornings, and the Great Soča Gorge on no day at all.
Sunreach is a 3D and AR sun tracker for iPhone and iPad, coming soon to the App Store. This guide describes the current app; planned upgrades are listed separately. Terrain coverage varies by location.
What is golden hour, exactly?
Golden hour is the period when the sun's centre is between −4° and +6° of true altitude, when sunlight travels through so much air that it turns warm and soft. A morning golden hour on 20 March lasts 40 min in Singapore, 57 min in Ljubljana and 1 h 20 min in Oslo.
Definitions vary between apps: some start golden hour at sunrise (0° to +6°), Sunreach and several photo planners use −4° to +6°, which includes the first warm light on clouds and high peaks before sunrise. Blue hour is −6° to −4°. Morning golden hour with a flat horizon, from the same engine:
| Place | 20 March | 21 June | 21 December |
|---|---|---|---|
| Singapore (1° N) | 40 min (06:56–07:36) | 43 min (06:47–07:30) | 44 min (06:47–07:31) |
| Los Angeles (34° N) | 49 min (06:41–07:30) | 55 min (05:24–06:19) | 56 min (06:37–07:33) |
| Ljubljana (46° N) | 57 min (05:48–06:45) | 1 h 9 min (04:48–05:57) | 1 h 12 min (07:19–08:31) |
| London (52° N) | 1 h 4 min (05:44–06:48) | 1 h 22 min (04:15–05:37) | 1 h 27 min (07:38–09:05) |
| Oslo (60° N) | 1 h 20 min (05:54–07:14) | 2 h 11 min (03:02–05:13) | 2 h 43 min (08:41–11:24) |
The golden hour times post has the evening times and more places.
Why does a valley miss golden hour?
Because the low sun is behind the mountains. If the skyline in the direction of sunrise or sunset is higher than 6°, the sun is already above 6° when it clears the ridge, so no low, warm sun ever reaches the spot.
In Bovec the first sun on 21 December arrives at 8° altitude, well past golden hour, and leaves at 11.3°. The sky over the town is golden at 07:24–08:37 and 15:31–16:43 that day, but the light on the ground is ordinary daylight or shade. The first low warm light of 2027 in Bovec comes on the evening of 14 January 2027, 15:57–15:57. In the Great Soča Gorge the slopes are steeper still: no low sun reaches it all year.
Sunreach computes this for any spot on Earth, from the real terrain around it. Get the app ↓
Where do you find golden light in the mountains?
On high ground with a low skyline toward the sun: ridges, summits, high passes, and the far shore of lakes looking toward a low horizon. The valley floor gets golden light only where a gap in the mountains lines up with sunrise or sunset.
The direction moves through the year. At 46° N the sun rises about 54° (NE) in June and 124° (SE) in December, so a valley that opens to the east-north-east gets summer sunrises and none in winter. The peaks themselves catch the first and last light: on a clear evening the summits above Bovec glow while the town has been in shade for half an hour.
Why do the peaks glow pink after sunset?
Just after the sun sets, peaks facing away from it are lit by scattered, reddened light from the sky rather than direct sun, so they glow pink or red. Before that, the highest summits keep the last direct red light for a few minutes after the valley is in shade.
It appears on the side of the mountains facing away from the sun, typically while the sun is between about 0° and −4°, which is the first part of the −4° to +6° golden hour band. Snow and pale limestone show it best. Whether a valley sees it depends on whether the peaks are visible above the nearer slopes, not on when the sun reaches the valley floor.
Sunreach’s plan lists the peaks that keep the last light after your spot is in shade, for how long, and a go or don’t-go from the clouds: peak light and valley fog.
How do you plan golden hour in the mountains?
Check two things for your spot and date: the time the sun clears the skyline, and its altitude at that moment. If it is under 6°, you get golden light; if not, plan for shade and use the sunlit peaks instead.
Sunreach gives both directly: "sun on spot" times, the band of low warm light on the spot (the sun visible and below 6°), and the skyline with the day's sun path. On site, a fist at arm's length is roughly 10°: if the ridge toward the sunset is more than half a fist above the true horizon, there will be no low sun on you.
Frequently asked questions
How long is golden hour in the mountains?
In the sky, the same as elsewhere at that latitude (about an hour at 46° N). On a valley floor it is often zero: the sun clears the ridge only once it is above 6°. In 2027 Bovec has low warm light on 110 days, never more than 14 min.
Is golden hour at sunrise or sunset better in the mountains?
Whichever side has the lower skyline toward the sun. A spot on the east side of a valley looks west to the sunset over the valley; a spot on the west side gets the sunrise. Check the skyline in the sun's direction for the date.
Does golden hour start before sunrise?
With the −4° to +6° definition, yes: it begins when the sun is 4° below the horizon, about 20–25 minutes before sunrise at mid-latitudes, when high clouds and summits already catch warm light.
Sources
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