2.9 usable nights
1–4 in the middle half of years · 1.1 typically near a dark moon.
358 astronomical-dark hours in an average month
20-year trip-planning baseline
Best time to stargaze at Bismarck
August: 10.3 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
Bright skyBortle classes describe observed sky conditions; this brightness model does not establish a measured Bortle class.19.4–20.1 mag/arcsec²
The short answer
August has been strongest.
It averages 10.3 usable nights, versus 0.4 in June. A typical August lands between 9 and 13 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
3.4 usable nights
2–4 in the middle half of years · 1.1 typically near a dark moon.
292 astronomical-dark hours in an average month
2.9 usable nights
1–4 in the middle half of years · 0.7 typically near a dark moon.
266 astronomical-dark hours in an average month
4.2 usable nights
2–6 in the middle half of years · 1.4 typically near a dark moon.
199 astronomical-dark hours in an average month
6.2 usable nights
4–8 in the middle half of years · 2.6 typically near a dark moon.
136 astronomical-dark hours in an average month
0.4 usable nights
0–1 in the middle half of years · 0.1 typically near a dark moon.
63 astronomical-dark hours in an average month
8.6 usable nights
6–10 in the middle half of years · 2.6 typically near a dark moon.
106 astronomical-dark hours in an average month
10.3 usable nights
9–13 in the middle half of years · 3.7 typically near a dark moon.
177 astronomical-dark hours in an average month
10.3 usable nights
9–11 in the middle half of years · 3.5 typically near a dark moon.
243 astronomical-dark hours in an average month
5.6 usable nights
3–8 in the middle half of years · 2.0 typically near a dark moon.
302 astronomical-dark hours in an average month
3.0 usable nights
1–4 in the middle half of years · 1.4 typically near a dark moon.
335 astronomical-dark hours in an average month
2.2 usable nights
1–3 in the middle half of years · 0.6 typically near a dark moon.
372 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.