Rain

The Rain is the only true, ever-present danger to both the player and all other terrestrial creatures of the world. Each cycle begins with the screen monochromatically darkening and a deep thunderous rumbling growing ever louder, as well as a scattering of all creatures. The Rain is catastrophic and will either crush or eventually drown anything in its wake.

You must find shelter before it's too late...

Variation of rain
The arrival of the Rain will have different effects based on which screen the player is located in. In most outdoor regions, the Rain will directly appear to impact the player's movement, most severely in areas with no overhead cover. The Rain will kill the player faster depending on its strength. In most indoor regions, the Rain will cause a hurried flooding of the room with water. In this case, the only main threat (besides fleeing creatures) is eventually drowning beneath the water's surface. In particular areas such as Five Pebbles, the upper limits of The Wall, Sky Islands's Communications Array, the lowest subregion of Subterranean (Depths), and any shelter, the Rain has no effect. In The Exterior's subregions The Leg and The Underhang, instead of raining, the green sparks floating around the area will accelerate and bounce around at high velocity, typically stunning and then killing the player in a matter of seconds.

In the minute before the end of a cycle in areas where Rain occurs, the background will darken. At thirty seconds before the end of a cycle, vibrations of the oncoming Rain can be felt and heard. From here, the Rain will most commonly increase steadily in strength from a drizzle to a lethal downpour over 45 seconds after the last pip. Occasionally, however, the Rain will have an intermission, in which case the vibrations and Rain will stop shortly after the end of the cycle. This break will last about 10 seconds, ending when loud individual droplets are heard. Following this intermission, the Rain immediately jumps to its full strength and all underground regions will begin flooding.

Cycles
Each cycle in Rain World has a random duration, visible in the bottom left corner surrounding the karma symbol. The "pips" each represent 30 seconds, and each cycle can last a maximum of 26 pips with an extra 20 seconds not shown in the timer (13 minutes and 20 seconds). The minimum cycle length depends on the selected difficulty - Survivor and Hunter have a minimum cycle length of 13 pips (6 minutes and 40 seconds), while Monk has a higher minimum cycle length of 18 pips (9 minutes). The cycle timer can be seen at any time by viewing the map, and it will flash up automatically once half the cycle is gone.

Tips

 * It is possible to survive longer during the Rain in flooded underground rooms. Bubble weed can be used to prolong breath underwater while searching for shelter.