How the moon affects mob spawning in Minecraft

Minecraft's moon is a regular guest in player worlds, popping up at night in various phases depending on how many days have elapsed in-game. However, the moon isn't simply a cosmetic addition for nighttime or a gag dimension in April Fool's Day snapshots. On the contrary, the moon and the phases it appears in have a distinct effect on how mobs spawn, be they hostile or otherwise.

At the core of the mechanic, Minecraft mobs are influenced by how full the moon is when it appears in the night sky. This can result in certain mobs appearing more often, as well as allowing some mobs to appear with better equipment. Not every mob is affected by the moon, but it's not a bad idea to take note of how it influences certain mobs.

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How does the moon influence mob spawning in Minecraft?

Slimes spawning in a swamp under a full moon in Minecraft (Image via Mojang)

Each passing in-game day in Minecraft, the moon will pass through one of its eight stages of fullness, transitioning from a full moon to a new moon before reverting to a full moon through waxing and waning stages. Depending on how full the moon is on a certain night, certain mob behaviors are adjusted when they spawn, and it doesn't hurt to know these changes so that you can plan accordingly.

The following mob effects are in play depending on the fullness of the moon:

1. The number of slimes that spawn in swamp biomes is directly proportional to how full the moon is. Slimes will spawn the most often in swamps during a full moon, but during a new moon, they won't spawn in swamps at all. Keep in mind, however, that slimes spawning in their underground spawn chunks won't be influenced by the state of the moon; it only affects above-ground slimes in swamps.
2. As the moon grows fuller, skeletons and zombies that spawn in the game world are more likely to pick up items on the ground or spawn with higher-quality gear. This includes enchanted gear, and the enchanted weapons and armor will be stronger on average if zombies/skeletons spawn with them during a full moon. In Minecraft: Java Edition, spiders will spawn with a higher likelihood of having beneficial status effects, including invisibility. All of these hostile mob benefits will scale alongside the difficulty setting as well, making full moons particularly dangerous.
3. During a full moon, 50% of the cats that spawn will be black cats.

A moonrise over a forest in Minecraft (Image via Mojang)

Overall, it takes two hours and 40 minutes in-game for a full lunar cycle to take place in Minecraft, and players will want to capitalize on the moon's fullness under certain circumstances. Full moons make slimes appear more often in swamps, making a full moon in Minecraft a great opportunity for slime farming and collecting materials, but only if players are aware of the potential danger from hostile mobs as well.

Meanwhile, if you want a pet black cat and don't want to resort to spawn eggs in Creative Mode or the use of commands, searching villages during the full moon is a surefire way to find one to tame.