The weather app for the night sky
Knowday reads the cloud cover and the moon, then tells you when tonight's sky is actually clear and dark enough to be worth heading out.
Tonight · your sky
What matters under the stars
Is the sky actually clear?
Cloud cover is everything — a thin overcast hides the whole show. Knowday weights it above all else and reads tonight as clear, broken, or socked in.
How bright the moon is
A full moon washes out faint stars as surely as cloud. Knowday reads the moon phase and brightness, so a "clear" night near a full moon doesn't oversell what you'll see.
Dew on your optics
A high dew point fogs your lens and eyepieces mid-session. Knowday reads it so you know whether to bring a dew shield — a detail almost no weather app surfaces.
Comfort and steadiness
The overnight feels-like for how long you'll last out there, and the wind that shakes a telescope on a tripod — the quiet reads that make or break a long session.
How it works
It scores cloud cover first, then the moon's brightness, the dew point, the night feels-like, and the wind — a clean Clear verdict means a genuinely dark, clear sky, never just "no rain".
One honest limit: it reads the weather, not the light pollution — a dark-sky site always beats town, and steady "seeing" is its own thing the forecast can't fully call.
Stargazing is one of fourteen plans Knowday reads — walks and rides, the lawn, the garden, camping, the night sky, and the water.
See all plansNo catch
Free to use. No sign-up. Your location is only used to fetch your forecast.