2.5 usable nights
1–3 in the middle half of years · 0.4 typically near a dark moon.
354 astronomical-dark hours in an average month
20-year trip-planning baseline
Best time to stargaze at Coos Bay
July: 18.1 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.20.9–21.3 mag/arcsec²
The short answer
July has been strongest.
It averages 18.1 usable nights, versus 1.5 in December. A typical July lands between 16 and 20 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
2.3 usable nights
0–4 in the middle half of years · 0.5 typically near a dark moon.
292 astronomical-dark hours in an average month
2.8 usable nights
1–5 in the middle half of years · 1.1 typically near a dark moon.
271 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.
213 astronomical-dark hours in an average month
6.8 usable nights
4–9 in the middle half of years · 2.2 typically near a dark moon.
161 astronomical-dark hours in an average month
9.3 usable nights
7–12 in the middle half of years · 2.9 typically near a dark moon.
120 astronomical-dark hours in an average month
18.1 usable nights
16–20 in the middle half of years · 6.6 typically near a dark moon.
140 astronomical-dark hours in an average month
17.1 usable nights
15–19 in the middle half of years · 6.6 typically near a dark moon.
199 astronomical-dark hours in an average month
13.4 usable nights
11–16 in the middle half of years · 4.5 typically near a dark moon.
247 astronomical-dark hours in an average month
8.3 usable nights
6–11 in the middle half of years · 2.4 typically near a dark moon.
304 astronomical-dark hours in an average month
2.6 usable nights
0–5 in the middle half of years · 0.5 typically near a dark moon.
331 astronomical-dark hours in an average month
1.5 usable nights
0–2 in the middle half of years · 0.3 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.