8.9 usable nights
7–11 in the middle half of years · 3.0 typically near a dark moon.
339 astronomical-dark hours in an average month
20-year trip-planning baseline
Best time to stargaze at San Antonio
October: 14.6 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 urban skyBortle classes describe observed sky conditions; this brightness model does not establish a measured Bortle class.18.0–18.8 mag/arcsec²
The short answer
October has been strongest.
It averages 14.6 usable nights, versus 5.5 in May. A typical October lands between 10 and 19 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
6.8 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
6.7 usable nights
5–9 in the middle half of years · 2.5 typically near a dark moon.
296 astronomical-dark hours in an average month
5.8 usable nights
4–7 in the middle half of years · 2.3 typically near a dark moon.
241 astronomical-dark hours in an average month
5.5 usable nights
4–7 in the middle half of years · 1.7 typically near a dark moon.
244 astronomical-dark hours in an average month
11.2 usable nights
8–15 in the middle half of years · 3.2 typically near a dark moon.
181 astronomical-dark hours in an average month
10.3 usable nights
7–13 in the middle half of years · 4.2 typically near a dark moon.
224 astronomical-dark hours in an average month
12.3 usable nights
8–17 in the middle half of years · 4.3 typically near a dark moon.
248 astronomical-dark hours in an average month
13.6 usable nights
11–17 in the middle half of years · 4.3 typically near a dark moon.
267 astronomical-dark hours in an average month
14.6 usable nights
10–19 in the middle half of years · 5.4 typically near a dark moon.
310 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.
321 astronomical-dark hours in an average month
8.4 usable nights
5–11 in the middle half of years · 2.8 typically near a dark moon.
328 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.