Stargazing guide
How much cloud is OK for stargazing?
No single cloud percentage makes a night good or bad. What matters is how much cloud is forecast during the hours you plan to observe, and what you want to see.
By The Star Window · Fact checked 2026-11-07 · Accountability and corrections
Why there is no one cutoff
The same amount of cloud means different things for different nights and goals:
- The target. The Moon and planets are far brighter than the sky behind them, so a passing gap is enough.
- The timing. A window average can hide a cloud-free first hour followed by a cloud-filled last hour, or the reverse. Observing in the open hours can work even when the average looks high.
- Where you are. Near a city, cloud reflects artificial light back down.
Forecast cloud is not the same as reported conditions
A forecast is a model's estimate for the hours ahead. A weather station's report says what its sensors measured at a moment. The National Weather Service's automated airport stations (ASOS) measure cloud with a ceilometer, and their cloud reports reach only about 12,000 feet, so a station report can miss thin cloud higher than that. A station showing no cloud while you can't see faint stars is not a contradiction: the cloud may be above what the sensor reaches.
References[2]
How the forecast words cloud elsewhere
National Weather Service forecasts describe sky cover in eighths of the sky and use a fixed set of terms for each range. Their table is on the NWS forecast terms page.
References[1]
What The Star Window's verdict already includes
Each Go, Marginal or Skip verdict is based on a conditions score. The score compares the forecast cloud, Moon interference and how dark the sky gets as the Sun sets for each place's window. Local light pollution is not in the score. A Go verdict on a place with heavy city light still means a bright sky background.
The verdict is a forecast for tonight's window. It does not promise what the sky will do, and it is not a measurement of conditions where you are standing.
Put this guide to work
Questions and answers
Is half the sky covered OK for stargazing?
It depends on when and what. Half the sky covered for the whole window is a different night from a cloud-free first half and a covered second half. For the Moon and bright planets you can work the gaps. For the Milky Way or a meteor shower, use the hours in your window with the least cloud.
Why does the weather station show no cloud when I can't see stars?
Automated NWS airport stations report cloud only up to about 12,000 feet, so they can miss thin, high cloud. Light pollution, haze, smoke or the Moon can also hide faint stars without any cloud at all.
Does The Star Window's verdict include cloud?
Yes. The verdict comes from a conditions score that compares the forecast cloud, Moon interference and how dark the sky gets as the Sun sets for the window.
What cloud number should I look for?
The site doesn't set one, because the right amount depends on your target and on when the cloud arrives. Lower is better for faint targets.
References and revision record
- National Weather Service, Binghamton — Forecast Terms (sky cover)official source, checked 2026-11-07
- National Weather Service — ASOS ceilometer descriptionofficial source, checked 2026-11-07
- National Park Service — Light Pollutionofficial source, checked 2026-11-07
- National Park Service — Astronomyofficial source, checked 2026-11-07
- NASA Science — Skywatching FAQofficial source, checked 2026-11-07
Recommendations remain subject to current weather, local access rules, and the limits stated in this guide.