'When We Were Young' Festival Cancels First Date Over Strong Winds

Some fans who were hoping to see their favorite 2000s emo bands in Sin City this weekend are out of luck -- the date's been canceled ... all thanks to Mother Nature.

Organizers behind the "When We Were Young" festival announced Saturday that their same-day kickoff in Vegas was being nixed because of strong winds being cited by the National Weather Service -- this despite the gang saying they've been actively preparing for this.

It sounds like the gust speeds were simply going to be too high and dangerous -- upwards of 60 MPH, they say -- which has forced them to shut it down until tomorrow, Sunday the 23rd.

The show, for now, is supposed to carry on as scheduled for those ticketholders, as well as ones for next Saturday -- the 29th ... but the folks who had tickets for today will have to seek a refund, which festival honchos apologetically say will be issued within 30 days.

This year's lineup is jam-packed with bands that were all going to perform the same set times for both days -- including headliners Paramore and My Chemical Romance ... not to mention Avril Lavigne, Bring Me The Horizon, All-American Rejects, Jimmy Eat World, Dance Gavin Dance, Taking Back Sunday, AFI, We The Kings, Bright Eyes, A Day To Remember and more.