Quadrantids

On paper the Quadrantids win: ZHR 110 against the Perseids' 100, and a population index of 2.1 against 2.2, which means a slightly higher share of bright meteors. The catch is the window. Quadrantid activity spans 16 days against 39 for the Perseids, and the peak solar longitude is quoted to two decimal places (283.15°) — about a quarter of an hour of Earth's orbital motion. Being half a day off the peak costs you far more here than it does in August. Treat the Quadrantids as a single-night decision and the Perseids as a week-long one.

The radiant sits at declination +49.8°, so south of 40.2°S the radiant never rises at all. From Sydney at 33.9°S the radiant tops out at 6° above the horizon, which multiplies the rate by the sine of that angle — effectively nothing. From Johannesburg at 26.2°S it reaches 14°. This is a northern-hemisphere shower in practice, not just on paper.

Less than for most. r = 2.1 is the joint-lowest population index of the twelve showers on this site — shared with the April Lyrids — meaning Quadrantid meteors skew bright, so the shower survives a compromised sky better than a faint-rich one like the Southern delta-Aquariids at r = 3.2. A magnitude of extra sky darkness multiplies your Quadrantid count by 2.1 but multiplies a delta-Aquariid count by 3.2. If you only have one dark-sky trip in you, spend it on the faint-rich shower.

That is exactly the question this site answers rather than the calendar. The Quadrantids peak in the first days of January, when cloud climatology is at its worst across most of the northern mid-latitudes, and the sharp peak means there is no second chance a night later. Check the hourly cloud forecast for your own coordinates on the night; if it is above 70% the verdict here will say so and point you at the next shower with a usable Moon instead.

Judged only on how much of the Moon is lit at the peak instant: 2026 — 3 January 2026 (Moon 100% lit); 2027 — 4 January 2027 (Moon 12% lit); 2028 — 4 January 2028 (Moon 44% lit); 2029 — 3 January 2029 (Moon 89% lit); 2030 — 3 January 2030 (Moon 0% lit). The dark-Moon years are 2027 and 2030; the washed-out ones are 2026 and 2029. Moon illumination is the only one of the four factors that is knowable years ahead — cloud cover is not, and neither is whether you will be somewhere dark.

Because 110 is the zenithal hourly rate: what one observer would count under a magnitude 6.5 sky with the radiant straight overhead. Two corrections pull it down before you ever look up. Rate scales with the sine of the radiant altitude, so a radiant 30° up delivers half of what it delivers at the zenith. And the population index for this shower is r = 2.1, which means each magnitude of sky brightness you lose costs you a factor of 2.1 in the count. A suburban sky two magnitudes shallower than the reference therefore divides the rate by about 4.4. Real counts are typically 30–50% under the modelled figure even after those corrections.