Thankfully, it was a mild one.
Because he's got some more 'splainin' to do when his LAST explanation falls through:
When the apocalypse failed to occur on May 21, Camping was widely mocked and he called it "a very difficult time."
He has since insisted that his prediction was overall correct. On May 24 he clarified that a "spiritual" Judgment Day had begun three days earlier, placing the entire world under Christ's judgment, and said the Earth actually would be obliterated on Oct. 21.
October 21… gotcha.