When Is the Full Moon in December 2025 and How Bright Will It Appear

The last full moon of the year will reach its peak on December 4, 2025, marking the arrival of December’s Cold Moon. Astronomers confirm that this month’s full moon will also be a supermoon, appearing brighter and larger than usual. Many skywatchers in the United States and beyond are preparing to view this rare final supermoon of the year.

The Cold Moon will reach peak illumination at 6:14 p.m. ET, according to NASA. Even if the peak occurs before sunset in several regions, the supermoon will appear full and bright throughout the nights of December 4 and December 5.

Key Details About the December 2025 Full Moon

The main event arrives on December 4, 2025, when the full moon reaches its brightest point. NASA reports that December’s full moon is also a supermoon, meaning the moon is near perigee, its closest point to Earth in its orbit. This makes it appear up to 14 percent larger and about 30 percent brighter than a typical full moon.

December’s full moon is traditionally known as the Cold Moon. The Old Farmer’s Almanac notes the name comes from Indigenous communities including the Mohawk tribe, who associated the moon with the frigid conditions of early winter. Other traditional names include the Long Night Moon, Winter Maker Moon, and Frost Exploding Trees Moon.

Cloud cover may affect visibility in parts of the United States. As of December 3, the National Weather Service forecasts significant sky coverage across many regions on the night of December 4. Despite this, the moon will appear full for several days, giving observers additional viewing opportunities.

Just days after the supermoon, a Moon-Jupiter conjunction will occur on December 7. NASA says Jupiter will appear close to the moon in the eastern sky around 11 p.m. ET, creating another visually striking moment for skywatchers.

Supermoons can also influence tides. Jim Todd of the Oregon Museum of Science and Industry explains that especially high tides, often called king tides, occur when the sun, moon, and Earth align. December’s supermoon is expected to bring another round of these unusually high tides in some coastal areas.

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How the December Full Moon Affects the Month’s Skywatching Events

This final supermoon of 2025 sets the stage for a busy month of sky activity. The brightness of the full moon creates dramatic nighttime visibility but can limit the viewing of faint stars. However, the Moon-Jupiter alignment will remain easy to spot due to Jupiter’s brightness.

For observers tracking major celestial events, the next supermoon will not take long to arrive. The Old Farmer’s Almanac reports the following supermoons after December 2025: January 3, 2026; November 24, 2026; and December 23, 2026. This continues a streak of frequent supermoons during this period of the lunar cycle.

The December supermoon offers one final opportunity in 2025 to witness an enlarged and brightened full moon. Anyone hoping to see the Cold Moon should look toward the eastern horizon around nightfall on December 4 and again on December 5 for the clearest view.

FYI (keeping you in the loop)-

Q1: When is the full moon in December 2025?

The full moon peaks on December 4, 2025, at 6:14 p.m. ET. It will appear full for several nights surrounding the peak.

Q2: Why is December 2025’s full moon a supermoon?

It is a supermoon because the moon reaches perigee, making it appear brighter and larger in the sky than average.

Q3: What is the Cold Moon?

The Cold Moon is the traditional name for December’s full moon, used by Indigenous tribes to mark early winter conditions.

Q4: Will the December supermoon cause king tides?

Yes, elevated tides may occur due to the alignment of the sun, moon, and Earth. These unusually high tides are often called king tides.

Q5: When is the next supermoon after December 2025?

The next supermoon will occur on January 3, 2026, followed by two more in November and December 2026.