Stormy weather today is complicating air travel at San Francisco International Airport, a duty manager said. As of 12:30 p.m. Sunday, 25 flights -- nine departures and 16 arrivals -- had been cancelled, SFO duty manager Lily Wang said. Most other flights were running between 45 and 90 minutes behind schedule, she said. Regional flights were most heavily impacted by cancellations, Wang said. With bad weather forecast for the remainder of the day, flight delays at SFO were expected to accumulate and worsen into tonight, Wang said. Passengers were being advised to check the status of their flights before leaving for SFO today.