Travelers moving through San Francisco International Airport saw immediate impacts Friday as the Federal Aviation Administration ordered flight reductions nationwide because of the prolonged federal government shutdown.

A temporary ground stop Friday morning delayed inbound flights by more than an hour, while cancellations continued to climb.

Read more: How bad are SFO flight cancellations and delays today? See data by airline and route

Related: Latest updates from United, Delta, Southwest and American

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The FAA's 4% cut in air traffic - the first of several phases that could reach 10% by next week - is straining airports from the Bay Area to New York.

Here's the latest on airport schedule changes, tips for passengers  and what to expect at Bay Area airports:

As of 4:30 p.m., flights to SFO were delayed at their point of origin by an average of 52 minutes, according to FlightAware.

Southwest Airlines says it will cancel about 100 flights on Saturday and 150 on Sunday to comply with the FAA's nationwide flight reduction order issued during the government shutdown. The airline said it has already reduced its schedule by 4% through Monday across 34 of the 117 airports it serves. Most flights, however, will operate as scheduled."Nothing is more important to Southwest than the safety of our customers and employees," the airline said in a statement. "We know that these FAA-imposed cancellations can impact an important moment in your life. We appreciate your understanding."Southwest "proactively canceled" 120 flights on Friday, noting it was a "small portion of our daily schedule."

SFO flights to and from LAX had seen the highest number of cancellations and delays as of the early afternoon Friday, according to FlightAware data.