December's full moon to reach peak brightness in California sky - What you need to know

A strikingly large moon will soon illuminate Californias night sky. The final full moon of 2025 will also be a supermoon, appearing unusually bright and sizable to stargazers across the state. This marks the third consecutive month of larger-than-normal moons, following the October 6 harvest moon and November 5 beaver moon. Experts highlight this rare sequence as a special chance for skywatchers to witness another stunning lunar display.

Timing the December Supermoon in California

The 12th full moon of 2025 will reach its peak at 3:14 p.m. on Thursday, December 4, according to Time and Date.

Understanding a Supermoon

A supermoon occurs when a full moon aligns with its closest approach to Earth in its elliptical orbit, a point called perigee. During this time, the moon can appear up to 14% larger and 30% brighter than when it is at its farthest point, or apogee. At perigee, the moon is roughly 356,000 kilometers away from Earth, compared to 406,000 kilometers at apogee.

The Cold Moon Name

Decembers full moon is traditionally known as the Cold Moon, a name that traces back to the Mohawk people and reflects the drop in temperatures during the last month of the year. In the United States, it has also been called the Long Night Moon, Drift Clearing Moon, Snow Moon, Frost Exploding Trees Moon, and Hoar Frost Moon. In Europe, ancient pagans referred to it as the Moon Before Yule, connecting it to winter solstice celebrations.

Supermoon Sequence in 2025

This December cold moon is the third supermoon of 2025. California ranks sixth among U.S. states for optimal viewing, based on sky clarity, humidity, elevation, and darkness. New Mexico holds the top spot for supermoon visibility.

Weather Effects of the Supermoon

The unusually large winter moon can slightly influence coastal tides, producing modestly higher king tides along Californias shoreline.

Best Ways to View the Supermoon

The supermoon is easiest to spot along the eastern horizon shortly after sunset, around 4:45 p.m. Its impressive size is amplified by the moon illusion, where objects near the horizon appear larger than when overhead. To capture the most striking images, frame the glowing moon with hills, trees, or buildings. NASA recommends turning off phone flashes and focusing cameras directly on the moon, ideally using a tripod for stability.

Upcoming Supermoon in California

Californians wont need to wait long for another supermoon. The Wolf Full Moon on Saturday, January 3, 2026, will also be a supermoon, marking the fourth consecutive larger-than-normal moon to appear across the United States.

Author: Olivia Parker