Is tonight good for stargazing? 4 things to check before you go out

Last updated 31 Oct 2026 • By the Spider Astro team

Heading out and finding a cloudy sky, or a Full Moon so bright you can barely see any stars, happens all the time. Check these four things first — it takes under a minute.

1) Cloud cover — the biggest factor

Even a very dark sky is useless if clouds cover it. Look at the hourly cloud-cover percentage for the time you plan to observe. In Spider Astro, an average of about 25% or less counts as clear, 26–55% as partly cloudy, and above 55% as heavily clouded.

2) Moonlight — the brighter, the fewer faint stars

When the Moon is near full and above the horizon, its light washes out faint stars. To see the Milky Way or faint stars, pick nights when the Moon has not risen yet or has already set — especially the 3–4 nights either side of New Moon. The Moon itself, bright planets such as Venus, and the brightest stars still look fine under moonlight. More in Moon phases and stargazing.

New Moon and Full Moon dates (Thailand time):

Calculated from real celestial positions by this site's own calculator; small errors are possible. Check an official astronomy calendar before important plans.

3) Rain, fog and haze

Besides clouds, look at the chance of rain. In northern Thailand the early part of the year often brings smoke haze that dims the sky even without clouds, so check PM2.5 or the air-quality index as well — a cloud forecast alone cannot show this.

4) City lights and eye adaptation

City lights brighten the sky; the farther you are from them, the more stars you see (astronomers describe sky darkness with the 9-level Bortle scale). Once you arrive, give your eyes about 20–30 minutes to adapt, avoid screen light, and use a red torch instead of white light.

Let the app summarise it

The “Tonight’s sky” page in Spider Astro combines all of this into a 0–100 index, using cloud cover, rain chance and moonlight at your pinned location. 80 and above is excellent, 60–79 good, 40–59 fair, lower is poor. It also shows the best time slot, the planets you can see and the bright stars. Free, no sign-up.