8.2 usable nights
7–10 in the middle half of years · 2.5 typically near a dark moon.
340 astronomical-dark hours in an average month
20-year trip-planning baseline
Best time to stargaze at Brenham
October: 17.1 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.20.0–20.6 mag/arcsec²
The short answer
October has been strongest.
It averages 17.1 usable nights, versus 6.9 in March. A typical October lands between 13 and 21 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
7.0 usable nights
4–10 in the middle half of years · 2.4 typically near a dark moon.
283 astronomical-dark hours in an average month
6.9 usable nights
5–8 in the middle half of years · 2.5 typically near a dark moon.
295 astronomical-dark hours in an average month
7.8 usable nights
6–9 in the middle half of years · 3.1 typically near a dark moon.
240 astronomical-dark hours in an average month
7.2 usable nights
5–10 in the middle half of years · 2.5 typically near a dark moon.
237 astronomical-dark hours in an average month
12.4 usable nights
10–15 in the middle half of years · 3.5 typically near a dark moon.
180 astronomical-dark hours in an average month
12.1 usable nights
8–15 in the middle half of years · 4.3 typically near a dark moon.
216 astronomical-dark hours in an average month
13.5 usable nights
11–18 in the middle half of years · 4.7 typically near a dark moon.
248 astronomical-dark hours in an average month
14.8 usable nights
13–17 in the middle half of years · 5.0 typically near a dark moon.
265 astronomical-dark hours in an average month
17.1 usable nights
13–21 in the middle half of years · 6.2 typically near a dark moon.
310 astronomical-dark hours in an average month
10.3 usable nights
7–13 in the middle half of years · 3.5 typically near a dark moon.
322 astronomical-dark hours in an average month
8.1 usable nights
6–11 in the middle half of years · 3.1 typically near a dark moon.
333 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.