Four things decide whether you actually see meteors: how high the radiant climbs from where you are standing, how much of the sky the Moon washes out, whether cloud arrives in the hours that matter, and how bright your local sky already is. Most sites give you those four numbers. This one gives you the conclusion.
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Reading the radiant, the Moon, the cloud forecast and the sky brightness for your coordinates.
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| Local time | Radiant | Moon alt | Moon lit | Cloud | Meteors/hour |
|---|---|---|---|---|---|
| Working out tonight's hours for your location… | |||||
Radiant altitude, Moon altitude and Moon illumination are computed from the shower's tabulated radiant and a lunar ephemeris. Cloud cover comes from a weather forecast and is shown as n/a when no forecast is available for the hour — it is never assumed to be clear. How these numbers are produced.
The rate you see scales with the sine of the radiant's altitude. A radiant 30° above the horizon delivers half of what the same shower delivers overhead, and a radiant below the horizon delivers nothing at all — which is why the Perseids are a non-event south of 32°S.
A bright Moon does not reduce the number of meteors; it raises the sky background so the faint ones stop being visible. How much that costs depends on the shower's population index — a faint-rich stream loses far more than a bright-rich one.
A nightly average is useless. What matters is whether the two hours when the radiant is highest are clear. When no forecast is available for an hour, this site says so instead of assuming clear skies.
Every magnitude of light pollution divides your count by the shower's population index. Measured sky-brightness data is not connected yet, so this site shows no Bortle class rather than guessing one.
One email seven days before a peak so you can keep the night free, and one on the evening itself with the verdict for your location. If your sky is going to be hopeless that night, the second email tells you the next good night instead of pretending otherwise.