Rain

Rain occurs randomly and affects all surface biomes for its duration. Each Rain event begins at a random time and lasts for 24 in-game hours (24 real-world minutes), spanning both day and night portions. When a player is in a Snow Biome during Rain, it appears as a Blizzard, causing snowfall volume to increase.

Rain is primarily an aesthetic Surface effect: It displays Rain/Blizzard graphics, darkened ambient sun/moon light, and altered music. There are however some functional effects.

Rain does not actually produce new Water tiles, doesn't cause existing Water levels to rise, and has no effect on Lava or Honey tiles, but it does spawn some unique enemies or enemy variants, and certain Critters behave differently. Some comical effects include Zombies wearing rain coats; Slimes carrying umbrellas; and Goldfish walking upright on land, using their tail fins to casually shuffle about (swimming goldfish will exit water and walk, and walking goldfish will also spawn anew on land).

On the, rain has three different variations; Light Rain, regular Rain, and Heavy Rain. The heavier the rainfall, the dimmer the sunlight will be, with heavy rain causing noticeable darkness. These variations are only graphical, can be detected with a Weather Radio, and can change multiple times throughout a single storm.

Other effects include:
 * There is a +20% Fishing Power bonus in all liquid bodies during Rain.
 * Waterleaf blooms.
 * Worms spawn frequently in Forest biomes.
 * NPCs remain in their Houses, as if it were night.
 * If Rain coincides with a Blood Moon, Rain will appear to be red-colored.
 * If you exit to the title screen during Rain, it might show fog.

See below for a complete list of unique Rain spawns, including Hardmode spawns.

History
雨 Regen Pluie 장마 Deszcz Дождь