December’s full moon to reach peak in California sky. What you need to know about the Supermoon

Skywatchers in California are in for a treat as the final full moon of 2025 approaches, promising an unusually large and bright display. This full moon will also be a supermoon, marking the third consecutive month of extraordinary lunar appearances following the October harvest moon and November beaver moon. Experts say this rare sequence provides an exceptional chance to witness another dazzling moon in the night sky.

When to View the December Supermoon in California

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

Understanding a Supermoon

NASA explains that a supermoon happens when a full moon coincides with the moon's closest approach to Earth, known as perigee. At this time, the moon can appear up to 14% larger and 30% brighter than when it is at its farthest point, called apogee. During perigee, the lunar distance is approximately 356,000 kilometers, compared with roughly 406,000 kilometers at apogee.

The Name Cold Moon

The December full moon is traditionally called the cold moon, a term originating from the Mohawk people, reflecting the seasonal temperature drop at the end of the year. In the U.S., it has also been known as the long night moon, drift clearing moon, snow moon, frost exploding trees moon, and hoar frost moon. European pagans referred to it as the moon before Yule, connecting it with winter solstice celebrations of returning sunlight.

Supermoons in 2025

Decembers cold supermoon is the third supermoon of 2025. California ranks among the top 10 U.S. states for viewing this event, placing sixth on the Supermoon Visibility Index, which evaluates sky clarity, humidity, elevation, and darkness. New Mexico holds the top spot.

Effects on Tides

This unusually large moon may slightly influence Californias coastal tides, producing modestly higher king tides, according to the Old Farmers Almanac.

Tips for Viewing and Photography

National Geographic recommends observing the supermoon along the eastern horizon shortly after sunset, around 4:45 p.m. The moon appears especially large due to perigee and the moon illusion, which makes objects near the horizon look bigger. To capture striking photos, frame the moon against hills, trees, or buildings, keep your camera focused on the moon, switch off your phone flash, and use a tripod for stability.

Next Supermoon in California

The next supermoon will be visible in early January 2026. The wolf full moon on Saturday, January 3, will also reach supermoon status, marking four consecutive months of remarkable lunar displays across the U.S.

Author’s Analysis: December’s Cold Supermoon in California

The upcoming December full moon, known as the “cold moon,” will mark the third consecutive supermoon in 2025, offering California residents a rare sequence of lunar events. This alignment of full moons at perigee enhances both size and brightness, making the celestial display notably striking.

Peak brightness is expected at 3:14 p.m. on December 4, though the moon will appear most dramatic shortly after sunset along the eastern horizon. The combination of perigee and the “moon illusion” ensures an optimal viewing experience, particularly in locations ranked highly on the Supermoon Visibility Index, including California, which holds the sixth position nationwide.

While the visual impact is the main draw, the cold supermoon may also influence coastal tides slightly, producing modestly higher “king tides.” For photography enthusiasts, using stable equipment and framing the moon against foreground objects will maximize the visual effect.

Looking ahead, California will witness another supermoon in early January 2026, continuing this unique four-month lunar sequence and providing additional opportunities for observation and study.

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