Rain

For pages about eventful storms, please refer to Storm (disambiguation)

Locke sitting in the rain ("Pilot, Part 1")

Rain is a frequent occurrence in Lost, usually supporting dramatic effect and accompanying significant scenes or plot twists.

Occurrences

Desmond in the rain after being released from prison ("Live Together, Die Alone")

When Jack, Kate and Charlie are running from the Monster. ("Pilot, Part 1")
When Locke embraces the rain and the Monster appears immediately after. ("Pilot, Part 1")
When Edward Mars attacks Kate, and Jack and Kate argue over ending the marshal's suffering. ("Tabula Rasa")
When Michael tells Walt "I'm going to get your dog back as soon as it stops raining". Walt looks out from their shelter and it almost immediately stops. ("Tabula Rasa")
When Jack's mother tells him to go get his father in Australia. ("White Rabbit")
When Jack fights with Ethan. ("All the Best Cowboys Have Daddy Issues")
When Locke and Boone find the Hatch. ("All the Best Cowboys Have Daddy Issues")
When Ethan is shot by Charlie. ("Homecoming")
When Sawyer shoots Frank Duckett. ("Outlaws")
When Shannon tries to kill Locke. ("The Greater Good")
When Jack and others head to the Black Rock for dynamite. ("Exodus, Part 1")

When Shannon is shot by Ana Lucia. ("Abandoned") ("The Other 48 Days")
When Edward Mars is transporting Kate to jail and they almost hit the black horse. ("What Kate Did")
When Charlie attacks Sun. ("The Long Con")
When Claire, Kate, and Rousseau find the the Staff station. ("Maternity Leave")
When Sayid, Ana Lucia, and Charlie find the balloon. ("Lockdown")
When Jack and Kate journey to the line. ("S.O.S.")
When Christian Shephard and Ana go to visit the apparent mother of one of his children. ("Two for the Road")
When Desmond is released from military prison. ("Live Together, Die Alone")
When Desmond crashes his boat. ("Live Together, Die Alone")

When Locke picks up a hitchhiking Eddie. ("Further Instructions")
Desmond builds a lightning rod to protect Claire's tent after foreseeing a storm no one saw coming. ("Every Man for Himself")
When Kate slips through the bars of her cage to enter Sawyer's cage. ("Every Man for Himself")
When Kate calls Edward Mars from a phone booth. ("I Do")
When Kevin Callis calls Kate from his patrol car. ("I Do")
During Ben's surgery, whilst Pickett holds Sawyer at gunpoint. ("I Do")
When Kate and Sawyer start the run from Hydra Island but stop at the point of hope (reaching a beach). ("Not in Portland")
After Desmond confronts Charlie in his "flashback," he accurately predicts a sudden rainstorm. ("Flashes Before Your Eyes")
When Kate and Juliet get in a fight. ("Left Behind")
When Desmond, Hurley, Charlie and Jin are walking through the jungle looking for the parachutist just before Charlie triggers the trap. ("Catch-22")
When Charlie is considering quitting the band while changing a tire in the rain with Liam and the other Drive Shaft members when he hears "You All Everybody" played on the radio for the first time. ("Greatest Hits")
Charlie gets caught in a rainstorm and starts running through the streets. He sees Nadia being mugged in an alley and comes to her rescue, for which she calls him a hero. ("Greatest Hits")

When the survivors split between Locke's group and Jack's group and when the freighters land on the Island. ("The Beginning of the End")
When Locke's group takes a break on the way to the cabin. ("Confirmed Dead")
In 1996, when Desmond first begins to experience shifts between his present-day reality and the freighter in 2004. ("The Constant")
When Harper appears to Juliet during a downpour. ("The Other Woman")
When Richard Alpert comes to test young Locke. ("Cabin Fever")

When Jack goes to inquire Carole about what she knows about Aaron. ("The Little Prince")
When the remaining people on the island are teleported to 1988 from an unknown time. ("The Little Prince")

Locke, Desmond and Juliet have all accurately predicted the sudden rainstorms.

Locke tells Boone "It's going to start raining in one minute. You should turn back.". ("All the Best Cowboys Have Daddy Issues")
Desmond tries to explain his time-travelling to Charlie, saying "...and then it started to rain". Sure enough, it does. ("Flashes Before Your Eyes")
Juliet informs Kate "It's going to rain. Don't you think we should wait 'til morning?" before they encounter the smoke monster. ("Left Behind")
Locke tells Hurley "Storm is about to pass, Hugo", before it's truly passed. ("Confirmed Dead")
In "The Beginning of the End", when it begins to rain, Locke looks confused, as though it had caught him by surprise.

Simulated rain with fire hoses (Welcome to Oahu)

According to "Welcome to Oahu", it rained for 12 days straight during the filming of "Pilot, Part 1" and "Pilot, Part 2", and at times the set completely flooded and nearly destroyed equipment.
At the same time as natural rain was coming down, they were also simulating rain, by pointing several full-sized fire hoses at the actors.