December 'Cold Moon' Peaks Dec. 4 — See 2025's Final Supermoon

The December full moon — the Cold Moon — reaches peak illumination on Thursday, Dec. 4 at 6:14 p.m. ET and is the third and final supermoon of 2025. A supermoon occurs when the full moon coincides with lunar perigee and can appear up to about 14% larger and 30% brighter. The moon will look full on the night of Dec. 4 and for a day or two around it. Key phases: First quarter Nov. 28; Full Dec. 4; Last quarter Dec. 11; New Dec. 20.

08:03 AM, 11/25/2025Science

December 'Cold Moon' Peaks Dec. 4 — See 2025's Final Supermoon

The last full moon of 2025 — traditionally called the Cold Moon — will reach peak illumination on Thursday, Dec. 4, at 6:14 p.m. ET. This event will be the third and final supermoon of the year, according to Space.com.

When to watch

The moon will appear essentially full throughout the night of Dec. 4 and remain nearly full for a day or two before and after the peak time. The precise maximum occurs at 6:14 p.m. ET, but any clear evening around that date is a good opportunity for viewing. For striking photos, consider framing the moon near the horizon with trees, buildings or a landscape for scale.

What makes a supermoon?

A supermoon occurs when a full moon coincides with the moon's closest approach to Earth in its elliptical orbit, called perigee. NASA notes that at perigee a full moon can appear up to about 14% larger in apparent diameter and as much as 30% brighter than a typical full moon. The visual change is more pronounced in photographs and when the moon is viewed near the horizon, though the difference can be subtle to the naked eye.

Moon phases around the December full moon

Key lunar phases listed by Moon Giant:

First quarter: Nov. 28
Full moon: Dec. 4 (6:14 p.m. ET)
Last quarter: Dec. 11
New moon: Dec. 20

As of Nov. 24, observers reported a waxing crescent with roughly 14% illumination as the moon progressed toward full, according to Space.com.

Looking ahead

The first full moon of 2026 — the wolf moon — will peak on Saturday, Jan. 3, 2026, and is also expected to be a supermoon, offering a bright start to the new year.

Sources: Space.com, NASA, Moon Giant, The Old Farmer's Almanac.