A day of heavy rain and lightning resulted in 60 flight cancellations in and out of San Francisco International Airport on Thursday, including one flight bound for London that was struck by lightning, an airport duty manager said.

That flight, United Airlines Flight 930 bound for London's Heathrow Airport, left at 7:35 p.m. and was struck by lightning while flying over the ocean, duty manager Nancie Parker said.

The plane returned to San Francisco at 10 p.m. and the passengers were re-accommodated to a flight Friday. 

No passengers were injured in the lightning strike, Parker said.

In addition to the 60 canceled flights, 19 were diverted to refuel because they could not land in San Francisco, and 22 flights arrived after midnight, Parker said.

The airport will be catching up today on the lost traffic, but more rain and lightning still lingering in the area today could mean more flight delays, Parker said.

As of around 6 a.m., flights are still anticipated to be on time, but weather and lost traffic could mean more delays after 8 a.m.

"Hopefully today will be a better day if the weather cooperates," Parker said.