Astro-Observer

Meteor showers

Sigma Hydrid Meteor Shower

By Astro-Observer · Last reviewed November 8, 2026

Active
December 3 – December 20
Peak
Around December 8–9
Peak rate (ZHR)
7
Radiant
Hydra (8h 20m, +2°)
Speed
58 km/s (fast)
Parent comet
C/2023 P1 (Nishimura)
Best seen from
Both hemispheres
Best time
After midnight, best in the hours before dawn

Next peaks

Expected peak (UTC)Moon at peakMoonlight
December 9, 2026, around 10h New Moon, 0% lit Little or none
December 9, 2027, around 17h Waxing gibbous, 82% lit Bright Moon

Computed from the shower's peak solar longitude (λ☉ 257°). Real peaks can come a few hours early or late, and you will see meteors on the nights either side. The peak hour may be in daylight where you are; watch the darkest hours of the nearest night.

The Sigma Hydrids are a minor shower of fast meteors from near the head of Hydra, the Water Snake. They are active in the first three weeks of December, alongside the Geminids, and can be seen from either hemisphere.

Where the meteors come from

The meteors are linked to Comet Nishimura, which passed closer to the Sun than Mercury does and takes more than 400 years per orbit. John Greaves in England noticed that its orbit closely matches those of Sigma Hydrid meteors filmed by video cameras. The IAU Meteor Data Center lists it as the parent, though IMO names none.

When to watch

The shower runs from December 3 to 20. IMO's visual data put the maximum around December 9 or 10, while video data suggest a peak near December 6 and activity until about December 24 (see the table above for the Moon). The radiant rises in the late evening, so watch after midnight.

How to find the radiant

The radiant is about 10 degrees east-southeast of the bright star Procyon and about 5 degrees west-southwest of Hydra's head, a compact ring of faint stars south of Cancer that includes Sigma Hydrae. Face east before midnight and south around 3 a.m. (north from the Southern Hemisphere).

What to expect

With a ZHR of 7, expect perhaps 2 to 4 an hour from a dark site in the early morning, and one or two from the suburbs. They are fast, at 58 km/s, and the population index of 3.0 means most are faint, though IMO notes that some bright ones are seen repeatedly.

Viewing tips

  • Watch after midnight, when the radiant is higher.
  • Use the speed: Sigma Hydrids are clearly quicker than the medium-paced Geminids.
  • Pick a field where the Sigma Hydrid, Geminid and Monocerotid radiants do not line up.
  • Try several mornings from December 6 to 10 to cover both peaks.

History and notable displays

IMO says the shower is often thought very weak, yet its maximum ZHR reliably reaches 5 to 8. Comet C/2023 P1 (Nishimura) was discovered by the Japanese observer Hideo Nishimura on August 12, 2023, and within weeks Greaves had matched its orbit to 129 video meteor orbits. In 2024, Samantha Hemmelgarn, Peter Jenniskens and colleagues showed that the meteor orbits could have pointed observers to the comet about eight months before its discovery.

About the numbers. The ZHR (zenithal hourly rate) is how many meteors one observer would see in an hour under a perfectly dark sky with the radiant straight overhead. Real counts are almost always lower: under suburban skies, or with the radiant low, expect a half to a quarter of it, or less.

Sources

Checked November 8, 2026.