10.6 usable nights
8–12 in the middle half of years · 3.7 typically near a dark moon.
341 astronomical-dark hours in an average month
20-year trip-planning baseline
Best time to stargaze at Stephenville
October: 16.9 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.20.7–21.2 mag/arcsec²
The short answer
October has been strongest.
It averages 16.9 usable nights, versus 7.6 in May. A typical October lands between 14 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
8.6 usable nights
7–10 in the middle half of years · 2.8 typically near a dark moon.
285 astronomical-dark hours in an average month
9.1 usable nights
6–11 in the middle half of years · 2.8 typically near a dark moon.
291 astronomical-dark hours in an average month
8.5 usable nights
7–10 in the middle half of years · 3.1 typically near a dark moon.
240 astronomical-dark hours in an average month
7.6 usable nights
5–10 in the middle half of years · 2.5 typically near a dark moon.
219 astronomical-dark hours in an average month
11.7 usable nights
9–15 in the middle half of years · 3.8 typically near a dark moon.
180 astronomical-dark hours in an average month
12.9 usable nights
10–16 in the middle half of years · 4.7 typically near a dark moon.
199 astronomical-dark hours in an average month
14.8 usable nights
13–17 in the middle half of years · 5.3 typically near a dark moon.
247 astronomical-dark hours in an average month
14.6 usable nights
14–16 in the middle half of years · 4.8 typically near a dark moon.
260 astronomical-dark hours in an average month
16.9 usable nights
14–20 in the middle half of years · 5.8 typically near a dark moon.
310 astronomical-dark hours in an average month
13.1 usable nights
10–17 in the middle half of years · 3.9 typically near a dark moon.
325 astronomical-dark hours in an average month
9.4 usable nights
7–13 in the middle half of years · 3.3 typically near a dark moon.
345 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.