Purchase from May 25 through June 10, 2021, 11:59 p.m. Central Time.
Continental U.S., interisland Hawaii, San Juan, Puerto Rico, and international travel valid August 17 through November 5, 2021. Travel continental U.S. to/from Hawaii valid August 9 through November 5, 2021.
Continental U.S. travel blacked out September 3 and September 6, 2021. Travel Hawaii to continental U.S. blacked out August 9-15, 2021.
Except as otherwise specified, continental U.S. and interisland Hawaii travel is not valid on Fridays and Sundays. Travel to Ft. Myers/Naples, Ft. Lauderdale, Miami, West Palm Beach, Tampa, Orlando, Sarasota/Bradenton, Pensacola, Panama City, FL, Destin-Fort Walton Beach, FL, Savannah/Hilton Head, Myrtle Beach, SC, Steamboat Springs, CO, Montrose (Telluride/Crested Butte), CO, Las Vegas, Santa Barbara, CA, and Bozeman is valid only on Sundays through Wednesdays. Travel from Ft. Myers/Naples, Ft. Lauderdale, Miami, West Palm Beach, Tampa, Orlando, Sarasota/Bradenton, Pensacola, Panama City, FL, Destin-Fort Walton Beach, FL, Savannah/Hilton Head, Myrtle Beach, SC, Steamboat Springs, CO, Montrose (Telluride/Crested Butte), CO, Las Vegas, Santa Barbara, CA, and Bozeman is valid only on Tuesdays through Fridays. Travel between Ft. Myers/Naples, Ft. Lauderdale, Miami, West Palm Beach, Tampa, Orlando, Sarasota/Bradenton, Pensacola, Panama City, FL, Destin-Fort Walton Beach, FL, Savannah/Hilton Head, Myrtle Beach, SC, Steamboat Springs, CO, Montrose (Telluride/Crested Butte), CO, Las Vegas, Santa Barbara, CA, and Bozeman is valid only on Tuesdays and Wednesdays. Travel continental U.S. to/from Hawaii is valid Monday – Thursday. Travel to/from San Juan, Puerto Rico is valid Monday – Thursday. International travel is valid Monday – Thursday. Travel to Mexico is valid only on Sundays through Wednesdays. Travel from Mexico is valid only on Tuesdays through Fridays.
Check your destination here
Example from Atlanta:
Screenshot — made at Southwest.com on 05/26/2021