- Miami International Airport was set to remain closed after suffering water damage
- Irma grounds more than 12,000 flights, and more cancellations are expected.
- More than 8,000 flights were canceled in Florida alone
- The storm is expected to hit near Delta's hub in Atlanta.
- A weakened Irma is on track to hit near FedEx's hub in Memphis.
Hurricane Irma is grounding travelers as far away as London and Doha, and cancellations will likely continue well into the week.
Flights will be suspended at Miami International Airport, Florida's busiest, through Monday after the airport suffered "significant water damage," the airport's chief executive tweeted late Sunday.
Airlines on four continents have canceled around 12,600 flights through Tuesday because of the storm, according to plane tracker Flight Aware. That number is set to rise as a weakened yet still powerful Irma heads north near Atlanta — a Delta Air Lines hub and the world's busiest airport.
The National Hurricane Center has downgraded Irma to a Category 2 hurricane, but the storm is still barreling up Florida's west coast, bashing the state with heavy rains and fierce winds.
In Florida alone, airlines have called off nearly 9,000 flights to and from the state.
American Airlines said late Sunday that it is planning to resume flights from its Miami hub when it reopens on Tuesday. The carrier has so far cancelled close to 2,500 flights through next Friday because of the storm.
canceled its twice-daily flight from London to Miami on Sunday and Monday, while Qatar Airways said it won't fly its Doha-to-Miami round trip route on Monday.
The storm is moving northward, away from South Florida. However, it isn't clear when Miami International Airport, Florida's largest air travel hub, will reopen. A spokesman told CNBC the Transportation Security Administration must check for any damage, such as downed perimeter fences, before operations can resume.
South Florida is not just a hub for American Airlines, but it receives dozens of flights from carriers that serve Latin America and the Caribbean. Big regional carriers like Chile's Latam, Colombia-based Avianca and Panamanian carrier Copa have also canceled flights to Florida this weekend.
All of these airlines said they would waive change or cancel fees due to the storm.
The National Oceanic and Atmospheric Administration forecasts Irma will weaken to a tropical depression during the week, and could strike near Memphis — FedEx's hub — by midweek.