Pick any point in North America — or tap Near me — and Meteorcast scores tonight and the next fourteen nights for night-sky viewing. It combines cloud cover by layer, air transparency (smoke, dust, humidity and water vapour), light pollution, and the hours the moon is out of the way, then tells you in one sentence what is actually limiting the night and what you will be able to see.
That depends on four things at your exact location: how much cloud there is, how dark it gets (light pollution plus the moon), how clean the air is, and how many hours the moon is below the horizon. Meteorcast combines all four into one 0–100 score for tonight and the next two weeks, at any point you tap on the map.
Cloud cover is one of the least predictable fields in a weather model. It holds hour-by-hour timing for about three days, becomes a whole-night leaning for about a week, and beyond roughly ten days a point forecast is no better than the long-run average for that date. Meteorcast marks those boundaries in the night list rather than showing a precise-looking number it cannot support. The moon and the dark hours, by contrast, are exact for any date.
The hours when the sun is more than 18° below the horizon (true astronomical darkness) and the moon is also below the horizon. It is the single most useful number for the Milky Way, galaxies and nebulae — a cloudless night with a gibbous moon overhead is a completely different sky from the same night after moonset.
For faint targets, yes — the Milky Way and deep-sky objects need a dark sky. But the moon, the planets and double stars are essentially unaffected by moonlight or light pollution, so a bright-moon night is still a good night for Jupiter or Saturn. That is why the forecast shows a row of target icons rather than only one number.
A 1–9 scale of light pollution, where 1 is a pristine dark-sky site and 9 is an inner city. Meteorcast estimates it from a sky-brightness model for the exact point you pick, and folds it into the score along with moonlight and twilight.
Watching for a specific shower? The meteor forecast adds radiant altitude and expected hourly rates on top of the same sky model.