12.4 usable nights
10–15 in the middle half of years · 4.4 typically near a dark moon.
341 astronomical-dark hours in an average month
20-year trip-planning baseline
When to plan an observing trip to Las Cruces
October: 19.9 usable nights on average. A regional planning baseline, not a forecast for your trip.
Site darkness · modelled, not measured
Bright skyBortle classes describe observed sky conditions; this brightness model does not establish a measured Bortle class.19.5–20.2 mag/arcsec²
The short answer
October has been strongest.
It averages 19.9 usable nights, versus 5.8 in July. A typical October lands between 18 and 24 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
12.3 usable nights
10–15 in the middle half of years · 3.8 typically near a dark moon.
285 astronomical-dark hours in an average month
13.2 usable nights
10–17 in the middle half of years · 3.9 typically near a dark moon.
291 astronomical-dark hours in an average month
14.7 usable nights
12–17 in the middle half of years · 5.0 typically near a dark moon.
240 astronomical-dark hours in an average month
17.8 usable nights
15–20 in the middle half of years · 6.0 typically near a dark moon.
218 astronomical-dark hours in an average month
14.1 usable nights
11–17 in the middle half of years · 4.5 typically near a dark moon.
180 astronomical-dark hours in an average month
5.8 usable nights
4–8 in the middle half of years · 1.8 typically near a dark moon.
199 astronomical-dark hours in an average month
5.9 usable nights
3–7 in the middle half of years · 2.4 typically near a dark moon.
247 astronomical-dark hours in an average month
14.6 usable nights
12–17 in the middle half of years · 5.3 typically near a dark moon.
260 astronomical-dark hours in an average month
19.9 usable nights
18–24 in the middle half of years · 6.7 typically near a dark moon.
310 astronomical-dark hours in an average month
16.3 usable nights
15–19 in the middle half of years · 5.1 typically near a dark moon.
325 astronomical-dark hours in an average month
12.8 usable nights
9–17 in the middle half of years · 4.5 typically near a dark moon.
346 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.