11.3 usable nights
9–14 in the middle half of years · 3.4 typically near a dark moon.
341 astronomical-dark hours in an average month
20-year trip-planning baseline
Best time to stargaze at Plano
September: 16.6 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.17.8–18.5 mag/arcsec²
The short answer
September has been strongest.
It averages 16.6 usable nights, versus 8.0 in May. A typical September lands between 15 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
8.4 usable nights
6–11 in the middle half of years · 2.6 typically near a dark moon.
286 astronomical-dark hours in an average month
8.8 usable nights
6–11 in the middle half of years · 2.5 typically near a dark moon.
289 astronomical-dark hours in an average month
8.2 usable nights
6–10 in the middle half of years · 3.0 typically near a dark moon.
240 astronomical-dark hours in an average month
8.0 usable nights
5–11 in the middle half of years · 2.6 typically near a dark moon.
213 astronomical-dark hours in an average month
12.1 usable nights
10–14 in the middle half of years · 3.6 typically near a dark moon.
180 astronomical-dark hours in an average month
13.5 usable nights
12–17 in the middle half of years · 4.8 typically near a dark moon.
196 astronomical-dark hours in an average month
14.5 usable nights
13–17 in the middle half of years · 5.2 typically near a dark moon.
245 astronomical-dark hours in an average month
16.6 usable nights
15–19 in the middle half of years · 5.6 typically near a dark moon.
259 astronomical-dark hours in an average month
16.4 usable nights
14–19 in the middle half of years · 5.8 typically near a dark moon.
310 astronomical-dark hours in an average month
13.0 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
9.1 usable nights
7–11 in the middle half of years · 3.1 typically near a dark moon.
350 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.