Family Radio Worldwide leader Harold Camping claims that the Rapture - a belief that Jesus Christ will return and take the faithful to heaven before the unleashing of hell on Earth - will begin at 6pm local time across the world.
He says that a powerful earthquake will be felt before all the noble spirits are transported off the earth. Those left behind will suffer until October 21, when God will destroy the planet.
Earlier this year, Camping said: "Beyond the shadow of a doubt, May 21 will be the date of the Rapture and the day of judgment."
Family Radio Worldwide's website says: "Because the year 2011 AD is exactly 7,000 years after 4990 BC when the flood began, the Bible has given us absolute proof that the year 2011 is the end of the world during the Day of Judgment.
"Amazingly, May 21, 2011 is the 17th day of the second month of the Biblical calendar of our day. Remember, the flood waters also began on the 17th day of the 2nd month, in the year 4990 BC."
Camping previously predicted that the apocalypse would occur in 1994.