Astronomy Weather Forecast
Know which nights
will be clear.
Pxie's astronomy weather forecast covers cloud, transparency and seeing up to 72 hours ahead, rolled into one observing score, for any place on Earth.
Light pollution is free; forecasts are included from the Builder plan.
Coverage: Anywhere on Earth, up to 72 hours ahead.
Cloud cover forecast, seeing forecast and more.
Cloud cover forecast
Total cloud every three hours out to 72 hours, with a 1 to 5 scale from clear to overcast.
Transparency
How clear the air is for faint targets, on a 1 to 5 scale.
Seeing forecast
How steady the air is, in arcseconds, for sharp planets and stars.
Observing score
Cloud, transparency, seeing, darkness and moon combined into one 0 to 100 number.
Sky chart
A ready-made 72-hour colour strip chart image in local time.
How the cloud cover forecast works, and where it falls short.
The cloud cover forecast
Yes, it works. Pxie returns total cloud cover for any location on Earth every three hours out to 72 hours, with a clear 1 to 5 label from Clear to Overcast. It refreshes as new weather model runs arrive, and every response says how old the forecast is.
What to keep in mind
It is a forecast from a global weather model, not a measurement of the sky above you. The model works on a grid about 15 km across, so it can miss small or fast-moving clouds, and mountains and large lakes can create local cloud it does not capture. Accuracy falls as you look further ahead, so trust the next 24 to 48 hours most and treat day three as a trend.
Total cloud only
The forecast gives total cloud cover. It does not split cloud into low, mid and high layers, so a thin high haze and a thick low deck can look alike. For astronomy, read it together with the transparency score.
Seeing and transparency are estimates
Transparency and seeing are Pxie estimates derived from the weather forecast, not measured at your site. Local effects such as heat from buildings, dome turbulence and ground fog are not included. Use them to compare nights, then confirm on the day.
How to use it
Use the observing score to rank the coming nights, then check the cloud strip again on the day. Observatories, clubs and astro-tourism operators use it to decide which night to commit to.
More sky quality data.
Astronomy weather API →
Endpoints, code samples and credits for developers.
Cloud cover API →
Total cloud and a clear-to-overcast label, 72 hours ahead.
Light pollution API →
Bortle class and sky brightness for any location.
Sunrise sunset API →
Sun, moon and twilight timing for the same nights.
Who uses it
- Observatories and clubs plan sessions around clear, steady skies.
- Astrophotographers and astro-tourism promote and book the best nights.
- Telescope and astronomy apps give users one clear answer for tonight.
Jasper tonight: observing score 82
Clear after 22:00 · steady air
"Will the sky be clear and steady near Jasper tonight?"
Pxie answers with the get_sky_conditions tool. Environmental data MCP server →
Astronomy weather forecast questions.
How far ahead does the astronomy weather forecast go?
Up to 72 hours, in steps of 3 hours.
What is a seeing forecast?
It predicts how steady the air will be. Steady air gives sharp views of planets and double stars at high magnification.
Does the cloud cover forecast split low, mid and high cloud?
Not always. The main forecast gives total cloud cover, so we don't promise separate layers.
What does it cost?
Light pollution is free. Forecasts, the observing score and the sky chart are on the Builder plan.
Spend your nights
under clear skies.
Start free, or tell us about your observatory, tours or app.
Developers: Sky Quality API docs →