"We're here at the end of the security line, I'm in shock actually. We got here early to actually beat this," traveler Yvonne O'Hare said.
Friday is the busiest travel day for the Christmas weekend. Approximately 166,000 passengers will go in and out of SFO - about 45,000 more than a normal day.
Add in the rain and it's the perfect storm for dozens and dozens of delays and cancelations.
When asked what he's going to do, San Francisco resident Patricio Garcia said, "Hope that it doesn't happen what happened last year, which meant we had to catch a flight the next day."
Airport officials knew this would be a stressful time, so they brought in singer Miko Marks to get people in the holiday spirit.
The skies weren't calm above SFO during the morning rush. Huge puddles on the road, people hurrying to get inside.
However, not everyone was expecting the rain. "It's starting to rain now. I wasn't expecting the weather," San Francisco Mike Biondolillo said.