7.5 usable nights
5–10 in the middle half of years · 2.4 typically near a dark moon.
348 astronomical-dark hours in an average month
20-year trip-planning baseline
Best time to stargaze at Grand Junction
September: 15.4 usable nights on average. Use this seasonal climate baseline to choose a month, then use the live forecast to choose a night.
Site darkness · modelled, not measured
Brightened skyBortle classes describe observed sky conditions; this brightness model does not establish a measured Bortle class.19.8–20.5 mag/arcsec²
The short answer
September has been strongest.
It averages 15.4 usable nights, versus 5.0 in February. A typical September lands between 14 and 18 usable nights.
Record2005–2024 · 20 complete years
Usable nightAt least 3 astronomical-dark hours and NASA POWER nighttime cloud ≤30%
Dark-moon nightUsable night with ≤25% illumination at local solar midnight
ResolutionCERES SYN1deg 1° cloud grid; regional climate, not a campsite guarantee
Seasonal fingerprint
Usable nights by month
Month by month
5.0 usable nights
3–6 in the middle half of years · 1.6 typically near a dark moon.
290 astronomical-dark hours in an average month
5.7 usable nights
3–8 in the middle half of years · 1.4 typically near a dark moon.
279 astronomical-dark hours in an average month
6.8 usable nights
5–8 in the middle half of years · 2.0 typically near a dark moon.
232 astronomical-dark hours in an average month
8.0 usable nights
6–10 in the middle half of years · 2.0 typically near a dark moon.
186 astronomical-dark hours in an average month
12.2 usable nights
8–15 in the middle half of years · 4.0 typically near a dark moon.
177 astronomical-dark hours in an average month
9.9 usable nights
8–12 in the middle half of years · 3.4 typically near a dark moon.
186 astronomical-dark hours in an average month
11.1 usable nights
9–14 in the middle half of years · 3.8 typically near a dark moon.
219 astronomical-dark hours in an average month
15.4 usable nights
14–18 in the middle half of years · 5.4 typically near a dark moon.
250 astronomical-dark hours in an average month
13.7 usable nights
10–17 in the middle half of years · 4.5 typically near a dark moon.
307 astronomical-dark hours in an average month
10.9 usable nights
8–14 in the middle half of years · 3.5 typically near a dark moon.
329 astronomical-dark hours in an average month
6.6 usable nights
4–10 in the middle half of years · 1.6 typically near a dark moon.
366 astronomical-dark hours in an average month
Use the baseline honestly
Climate chooses the month. Forecasts choose the night.
The cloud product is a roughly 1° regional grid. It can reveal seasonality, but it cannot know a mountain ridge, valley fog pocket, locked gate, smoke event or the exact sky you will get.
Source: NASA POWER daily data, parameter CLOUD_AMT_NIGHT from the CERES SYN1deg cloud product. GoodSeeing calculates astronomical darkness and lunar illumination independently for each place.