The last supermoon of 2025 is set to light up the December sky, offering one of the year’s most striking lunar displays. Known as the Cold Moon, this full moon will appear noticeably larger and brighter as it reaches full illumination on Thursday, 4 December. The event marks the final in a trio of consecutive supermoons this year, rounding off an active period for skywatchers.

The moon will reach full phase at 8:20 a.m. EST (6:50 p.m. IST), but it will look full to observers on the nights of 3 and 4 December. Its proximity to Earth – happening just hours after the moon reaches perigee – will give it a more prominent glow and impressive apparent size, especially at moonrise shortly after sunset.

Why December’s full moon is called the Cold Moon

The December full moon has long been referred to as the Cold Moon, a name that reflects the onset of some of the chilliest nights of the year in the Northern Hemisphere. Other traditional names include the Long Nights Moon and the Moon Before Yule, referencing seasonal and cultural observances.

In 2025, the Cold Moon’s timing coincides with early winter evenings and long, dark nights, making the supermoon particularly eye-catching.

What makes it a supermoon

A supermoon occurs when a full moon aligns with the point in its elliptical orbit closest to Earth. During December’s event, the moon will sit roughly 357,218 kilometres from Earth – considerably closer than its average distance of 384,472 kilometres.

This makes the Cold Moon the second-closest full moon of the year. Although the moon is only around 10% nearer than usual, NASA notes that this subtle difference can make it appear up to 14% larger and around 30% brighter compared with the faintest full moon of the year. The effect is especially noticeable at moonrise, when the moon sits low on the horizon.

Why it will appear higher in the sky

This Cold Moon will also climb higher in the night sky than any other full moon of the year for observers in the Northern Hemisphere. Because a full moon rises opposite the sun and December’s solstice places the sun at its lowest annual point, the moon reaches its highest arc at night. This creates ideal conditions for extended viewing and dramatic overhead visibility.

When and where to watch the Cold Supermoon

The most striking views of the supermoon will occur shortly after moonrise on Friday, 5 December for most locations. Watching as it emerges above the eastern horizon enhances the moon illusion – a visual effect that makes the moon seem larger than it truly is. Though scientists have yet to fully explain this phenomenon, it remains a highlight for photographers and stargazers.

Sample timings include:

  • New York: Sunset at 4:29 p.m. EST; moonrise at 4:56 p.m. EST
  • Los Angeles: Sunset at 4:43 p.m. PST; moonrise at 5:27 p.m. PST

For exact timings, observers are encouraged to use a moonrise calculator specific to their region.

Why the moon looks even bigger on the horizon

Even without a supermoon, the moon often looks larger when it is low in the sky due to the moon illusion. Nearby trees, buildings and landscape features create visual references that trick the brain into perceiving a bigger moon. When combined with the moon’s shorter distance from Earth in December, the effect becomes even more striking.

A notable year for lunar events

The Cold Moon concludes a particularly eventful year for lunar observers, which included three supermoons and two total lunar eclipses. The March and September blood moons were among the major highlights of 2025. The sequence of supermoons will continue into the new year, beginning with the Wolf Moon on 3 January 2026 – the fourth supermoon in a row.

Tips for watching the December Cold Supermoon

To get the best views of the final supermoon of 2025: 

  • Pick the right spot: Choose a location with an unobstructed view of the eastern horizon – beaches, open fields and elevated ground work well.
  • Know your timing: Check local moonrise schedules to plan your viewing.
  • Watch early: The moon looks most dramatic when it first rises due to the moon illusion.
  • Bring equipment if you like: Binoculars or a zoom-capable camera can enhance the details, but the event is easily visible to the naked eye.
  • Dress warmly: December nights can be harsh, so bundle up if you plan to stay outside for a while.

(With inputs from AP)