How dark is the sky at Teton County?

Modelled zenith brightness from the 2024 World Atlas of Artificial Night Sky Brightness puts Teton County at about 20.31 mag/arcsec², roughly Bortle class 5. That is an approximation derived from satellite data, not a field measurement; it is certified by DarkSky International as an International Dark Sky Community.

How far is Teton County from Salt Lake City?

About 316.8 km in a straight line, heading north from Salt Lake City. Using a 1.3 road-detour factor and staged average speeds that is roughly 411.8 km and 4.8 h of driving — an estimate, not a routed drive time.

When is the next moon-free dark window at Teton County?

The next stretch of essentially moon-free dark hours runs Nov 2–15 (14 nights), computed from Moon phase and altitude with Skyfield and JPL DE440s. Cloud cannot be known that far ahead; the live seven-night forecast on this page shows real cloud cover once a window is close.

What is the clearest month at Teton County?

Over 2021–2025, July (87%), September (77%), August (74%) had the highest share of nights with astronomical darkness that stayed clear (weighted cloud cover ≤ 20%); across the year it was 51%. ERA5 reanalysis via Open-Meteo — historical frequency, not a forecast.

United States · International Dark Sky Community

Stargazing at Teton County

How dark this certified sky really is, how far it is from the nearest cities, a live seven-night forecast for the site itself, and the moon-free nights worth planning around. Official DarkSky International page ↗

Sky at the siteBortle ≈ 520.31 mag/arcsec² · 2024 atlas

From Salt Lake City~4.8 h316.8 km straight-line · head north · estimated

Next moon-free windowNov 2–1514 nights · moon geometry only

How dark the sky really is at Teton County

Modelled zenith brightness at the site's coordinates is 20.31 mag/arcsec², which maps to roughly Bortle 5 (what each level means). This is an approximation from the 2024 light-pollution atlas, not a field measurement — and it describes the single point DarkSky lists, not the darkest corner of the community.

Modelled zenith brightness puts this spot at Bortle 5 — a suburban sky where the Milky Way is only faintly visible at best. The international dark sky community designation recognises responsible lighting and education, not a pristine sky; the Moon, planets, double stars and bright clusters are the realistic targets, and the atlas value at the site centre may not reflect its darkest corners.

Getting to Teton County

The nearest cities we publish guides for, with the direction to head and a rough drive estimate.

From Salt Lake City
head north · 316.8 km straight-line · ≈411.8 km by road · ≈4.8 h · weekend trip
From Denver
head north-west · 634.7 km straight-line · ≈825.1 km by road · ≈9.1 h · weekend trip

Estimated from straight-line distance x a 1.3 road-detour factor and staged average speeds (40 km/h leaving town, 70 km/h regional, 95 km/h highway). It is a rough guide, not a routed drive time.

The next seven nights at Teton County

Loading the live forecast…

Plan the next 90 days at Teton County

Moon-free dark windows are astronomy — computable years ahead. Cloud is not: beyond the 16-night forecast nobody knows the weather, and we won't pretend to. What five years of reanalysis can say is how often each month's nights actually stayed clear here.

Nov 2–1514 moon-free nights27% of November nights here stayed clear (2021–2025)
Dec 2–1413 moon-free nights19% of December nights here stayed clear (2021–2025)
Dec 31 – Jan 1314 moon-free nights19% of December nights here stayed clear (2021–2025)

Clear nights by month, 2021–2025

Jan28%
Feb28%
Mar36%
Apr51%
May60%
Jun73%
Jul87%
Aug74%
Sep77%
Oct53%
Nov27%
Dec19%

Clearest months historically: July (87%), September (77%), August (74%); across the year 51% of nights with astronomical darkness stayed clear.

"Clear" = weighted cloud cover (low 0.5 / mid 0.3 / high 0.2) ≤ 20% across the night's astronomical darkness. ERA5 reanalysis via Open-Meteo Archive, 2021–2025 (CC BY 4.0) — historical frequency, not a forecast. Once a window comes within 16 nights, the live forecast above takes over.

Put Teton County's dark-sky nights on your calendar

Every month has a stretch of nights when the Moon leaves the dark hours at Teton County essentially moon-free. Subscribe once and each window lands in your own calendar, about a year ahead — no account, no email.

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moon & darkness geometry only — cloud can't be known this far out; check the live forecast above when a window gets close

Questions people ask about Teton County

How dark is the sky at Teton County?: Modelled zenith brightness from the 2024 World Atlas of Artificial Night Sky Brightness puts Teton County at about 20.31 mag/arcsec², roughly Bortle class 5. That is an approximation derived from satellite data, not a field measurement; it is certified by DarkSky International as an International Dark Sky Community.
How far is Teton County from Salt Lake City?: About 316.8 km in a straight line, heading north from Salt Lake City. Using a 1.3 road-detour factor and staged average speeds that is roughly 411.8 km and 4.8 h of driving — an estimate, not a routed drive time.
When is the next moon-free dark window at Teton County?: The next stretch of essentially moon-free dark hours runs Nov 2–15 (14 nights), computed from Moon phase and altitude with Skyfield and JPL DE440s. Cloud cannot be known that far ahead; the live seven-night forecast on this page shows real cloud cover once a window is close.
What is the clearest month at Teton County?: Over 2021–2025, July (87%), September (77%), August (74%) had the highest share of nights with astronomical darkness that stayed clear (weighted cloud cover ≤ 20%); across the year it was 51%. ERA5 reanalysis via Open-Meteo — historical frequency, not a forecast.

Place name and coordinates: DarkSky International (reviewed 2026-07-15, data 2026-10-13). Light pollution: David Lorenz, World Atlas 2024 (EOG VIIRS, CC BY 4.0), approximate. Cloud: Open-Meteo.com (CC BY 4.0). Moon and darkness geometry: Skyfield + JPL DE440s, computed locally. Drive times are estimates, not routes.