How dark is the sky at Devils River State Natural Area — Del Norte Unit?

Modelled zenith brightness from the 2024 World Atlas of Artificial Night Sky Brightness puts Devils River State Natural Area — Del Norte Unit at about 21.95 mag/arcsec², roughly Bortle class 2. That is an approximation derived from satellite data, not a field measurement; it is certified by DarkSky International as an International Dark Sky Sanctuary.

How far is Devils River State Natural Area — Del Norte Unit from San Antonio?

About 246.5 km in a straight line, heading west from San Antonio. Using a 1.3 road-detour factor and staged average speeds that is roughly 320.4 km and 3.8 h of driving — an estimate, not a routed drive time.

When is the next moon-free dark window at Devils River State Natural Area — Del Norte Unit?

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 Devils River State Natural Area — Del Norte Unit?

Over 2021–2025, July (90%), September (90%), June (87%) had the highest share of nights with astronomical darkness that stayed clear (weighted cloud cover ≤ 20%); across the year it was 75%. ERA5 reanalysis via Open-Meteo — historical frequency, not a forecast.

United States · International Dark Sky Sanctuary

Stargazing at Devils River State Natural Area — Del Norte Unit

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 ≈ 221.95 mag/arcsec² · 2024 atlas

From San Antonio~3.8 h246.5 km straight-line · head west · estimated

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

How dark the sky really is at Devils River State Natural Area — Del Norte Unit

Modelled zenith brightness at the site's coordinates is 21.95 mag/arcsec², which maps to roughly Bortle 2 (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 sanctuary.

This is about as dark as the atlas gets: at Bortle 2 the Milky Way casts visible shadows on moonless nights, the zodiacal light is obvious and the faintest deep-sky objects are within reach of modest optics. Your own light — and the Moon — will be the limiting factor, not the site.

Getting to Devils River State Natural Area — Del Norte Unit

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

From San Antonio
head west · 246.5 km straight-line · ≈320.4 km by road · ≈3.8 h · weekend trip
From Austin
head west · 312.9 km straight-line · ≈406.8 km by road · ≈4.7 h · weekend trip
From Dallas
head south-west · 506.4 km straight-line · ≈658.3 km by road · ≈7.4 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 Devils River State Natural Area — Del Norte Unit

Loading the live forecast…

Plan the next 90 days at Devils River State Natural Area — Del Norte Unit

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 nights65% of November nights here stayed clear (2021–2025)
Dec 2–1413 moon-free nights64% of December nights here stayed clear (2021–2025)
Dec 31 – Jan 1314 moon-free nights64% of December nights here stayed clear (2021–2025)

Clear nights by month, 2021–2025

Jan73%
Feb68%
Mar70%
Apr67%
May63%
Jun87%
Jul90%
Aug81%
Sep90%
Oct81%
Nov65%
Dec64%

Clearest months historically: July (90%), September (90%), June (87%); across the year 75% 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 Devils River State Natural Area — Del Norte Unit's dark-sky nights on your calendar

Every month has a stretch of nights when the Moon leaves the dark hours at Devils River State Natural Area — Del Norte Unit 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 Devils River State Natural Area — Del Norte Unit

How dark is the sky at Devils River State Natural Area — Del Norte Unit?: Modelled zenith brightness from the 2024 World Atlas of Artificial Night Sky Brightness puts Devils River State Natural Area — Del Norte Unit at about 21.95 mag/arcsec², roughly Bortle class 2. That is an approximation derived from satellite data, not a field measurement; it is certified by DarkSky International as an International Dark Sky Sanctuary.
How far is Devils River State Natural Area — Del Norte Unit from San Antonio?: About 246.5 km in a straight line, heading west from San Antonio. Using a 1.3 road-detour factor and staged average speeds that is roughly 320.4 km and 3.8 h of driving — an estimate, not a routed drive time.
When is the next moon-free dark window at Devils River State Natural Area — Del Norte Unit?: 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 Devils River State Natural Area — Del Norte Unit?: Over 2021–2025, July (90%), September (90%), June (87%) had the highest share of nights with astronomical darkness that stayed clear (weighted cloud cover ≤ 20%); across the year it was 75%. 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.