Hurricane Harvey strengthened to a Category 3 storm Friday, just hours before it was expected to hit the shores of the Texas Gulf coast.

The storm is expected to unleash several days of high winds, flash flooding, storm surges and up to three feet of rain. With about 700,000 people living in the hurricane warning zone — roughly half in Corpus Christi — traffic backups were reported as people move inland.

Harvey is cause for major concern in Texas, but the hurricane's impact may also be felt in other states.

Fortunately, there are no flights currently canceled or delayed at the Sacramento International Airport (SMF) or the San Francisco International Airport (SFO), but most big U.S. airlines are waiving change fees for customers whose flights may be impacted by Harvey.

The policies vary by airline, but most eligible customers are permitted to make one change to their itineraries without paying change fees that can cost $200 or more per passenger. Many airline policies generally allow fliers to move their flights without paying a fare difference, but there's usually a travel window where the change is allowed.

In the case Harvey does start to impact airports in Northern California, there are resources available to stay prepared. It's important for customers who have plans to fly either to or from the hurricane region in the next few days, to keep in touch with the airline hosting their flight. Customers can call the airline and check a flight status online or on an app if available.

To see which airlines have enacted flexible airline re-booking policies click HERE.

To get updates on a flight, check out Flight Tracker and click HERE.