What does ZHR mean when describing the 2026 Perseid meteor shower?

ZHR means Zenithal Hourly Rate when describing the 2026 Perseid meteor shower.

The term is a standardized way to compare meteor-shower activity. It estimates the number of meteors a single observer could see in one hour if the sky were perfectly clear and dark, the limiting stellar magnitude were about 6.5, and the shower radiant were at the zenith.

Because those conditions rarely occur together, ZHR is not a promise of the number visible from a garden, balcony, or city. Observers usually see fewer meteors because of light pollution, obstructions, clouds, haze, and the radiant’s position above the horizon.

The Perseids’ commonly quoted ZHR is about 100 at maximum activity. This figure helps compare the Perseids with other showers, but actual counts vary from year to year and from one observing site to another.