Stargazing Forecast

What Is a Stargazing Forecast?

A standard weather forecast tells you if it will rain. A stargazing forecast tells you if the sky is worth looking at.

The difference matters because stargazing has specific requirements that generic weather apps don't address. You need to know about cloud layers (not just total cover), moon timing and brightness, when astronomical darkness begins and ends, wind speed at ground level (which affects telescope stability), and humidity (which fogs optics and reduces transparency).

Clear Skys combines all these factors into a single score from 0 to 100 for each hour of the night. It identifies the best viewing window — the longest continuous stretch of good conditions — so you can plan around it. And it runs forward 7 days, so you can pick the best night of the week rather than gambling on tonight.

Why Not Just Use a Weather App?

Weather apps report cloud cover as a single percentage, but not all cloud is equal for astronomy. A layer of thin high cirrus at 8,000m reduces contrast on faint objects but still allows planetary observing. A solid deck of low stratus at 1,500m blocks everything. Clear Skys uses three-layer cloud data (low, mid, high) from Open-Meteo, weighted to reflect the impact on observing: low cloud counts for 50% of the cloud score, mid-level for 35%, and high for 15%.

Weather apps also don't factor in the moon. A "clear night" according to your phone could be a washout for deep-sky astronomy if the moon is 90% illuminated and above the horizon all night. Clear Skys subtracts a moon penalty from the score based on illumination and overlap with your darkness window.

Finally, weather apps don't tell you when darkness starts and ends. The gap between sunset and astronomical darkness can be over two hours at mid-latitudes. Heading out at sunset is a common beginner mistake — the best observing doesn't start until the sun is 18° below the horizon.

What's Included in a Clear Skys Forecast

Every forecast gives you the scored conditions (0–100), the best viewing window with start and end times, a verdict ("Go out tonight" / "Probably skip tonight"), all visible planets with peak altitude and best observation time, aurora probability if you're at a relevant latitude, bright satellite passes including the ISS, moon phase and rise/set times, a full hourly breakdown showing how conditions change through the night, and a 7-day overview so you can plan ahead.

You can also switch between five observer profiles — General, Astrophotography, Visual, Planetary, and Aurora — each of which reweights the scoring factors for your type of observing. An astrophotographer gets penalised more for wind (it blurs long exposures) and moonlight (it raises the sky background). A planetary observer barely cares about moonlight and tolerates higher wind.

Forecasts are available for any location worldwide. The 102 city landing pages cover major destinations, but you can search for any address, village, or GPS coordinate.

Popular Stargazing Forecasts

Check tonight's conditions for these locations, or search for your own: