Supermoon to reach its peak in the California sky. Information about December's full moon you should know

A strikingly large moon is set to illuminate Californias night skies soon. The final full moon of 2025 will also be a supermoon, making it appear brighter and bigger than usual for local observers.

This marks the third consecutive larger-than-average moon visible in the state, following the October 6 harvest moon and the November 5 beaver moon. Experts describe this sequence as an uncommon chance for skywatchers to witness another spectacular lunar display.

When to Watch the December Supermoon

The last full moon of 2025 will reach its maximum brightness at 3:14 p.m. on Thursday, December 4, according to online astronomical calendars.

Understanding the Supermoon

A supermoon happens when a full moon aligns with the moons closest point to Earth, known as perigee. At this position, the moon can appear up to 14% larger and 30% more luminous compared to when it is at its farthest point, called apogee. During perigee, the moon is roughly 356,000 kilometers from Earth, versus about 406,000 kilometers at apogee.

The Cold Moon Explained

Decembers full moon is traditionally called the Cold Moon, a name originating from the Mohawk people that reflects the seasonal drop in temperatures during the last month of the year. Other historical names in the United States include the Long Night Moon, Drift Clearing Moon, Snow Moon, Frost Exploding Trees Moon, and Hoar Frost Moon.

European pagans referred to this lunar phase as the moon before Yule, linking it to winter solstice celebrations and the return of longer daylight hours.

Supermoon Viewing in 2025

The December Cold Supermoon is the third in a series of three supermoons occurring in 2025. California ranks among the top ten U.S. states for observing this event, placing sixth in the Supermoon Visibility Index, which considers sky clarity, humidity, elevation, and darkness.

Effects and Observation Tips

This unusually large winter moon can slightly increase tides along Californias coast, known as king tides, though the effect is minimal.

For the best viewing experience, watch the supermoon near the eastern horizon shortly after sunset, around 4:45 p.m. The moon illusion will make it appear even larger near the horizon. Photographers can enhance their shots by framing the moon against trees, hills, or buildings. Experts recommend turning off phone flashes, focusing cameras directly on the moon, and using a tripod for stability.

Next Supermoon in California

The next supermoon will appear in early January. The Wolf Full Moon on Saturday, January 3, 2026, will also be a supermoon, offering another opportunity for Californians to witness a remarkable lunar display, continuing the streak of consecutive supermoons across the U.S.

Analysis: December’s Cold Supermoon and Its Significance

The upcoming December full moon in California is not just any lunar event—it is a supermoon, the third consecutive larger-than-average moon in 2025. Following the October Harvest Moon and November Beaver Moon, this sequence provides an uncommon viewing opportunity for local skywatchers.

Technically, the supermoon occurs when the full moon coincides with its perigee, the closest point to Earth. At roughly 356,000 kilometers, the moon will appear up to 14% larger and 30% brighter than when at apogee. This enhances both visual spectacle and photographic potential for observers.

Known traditionally as the Cold Moon, December’s lunar phase carries historical and cultural significance. Indigenous peoples, as well as European pagans, attributed symbolic meaning to this full moon, often linking it to seasonal changes and the winter solstice.

California ranks sixth nationally for optimal supermoon visibility due to favorable sky clarity, elevation, and darkness. While minimal, the event may slightly influence coastal tides, known as king tides. For the best viewing, observers should look near the eastern horizon shortly after sunset, using techniques to reduce light interference and stabilize photography equipment.

Looking ahead, the lunar spectacle continues with the Wolf Full Moon on January 3, 2026, also a supermoon. This extends the rare sequence of consecutive supermoons, giving Californians a prolonged chance to engage with these remarkable celestial displays.

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• Supermoon to peak soon in California sky. What to know about December’s full moon