The Atlas V rocket lit up the night sky at about 11:15 p.m. Thursday, lifting off from Vandenberg Air Force Base toward low-Earth orbit.
The 19-story-tall rocket carried a payload for the National Reconnaissance Office, which operates the nation's system of intelligence-gathering satellites. The agency has not released any details about the payload.
A California cold snap had threatened a possible delay, but the rocket took off within moments of the opening of its launch window.
Thursday's launch was the second time an Atlas 5 rocket has lifted off from the West Coast this year. Overall, there have been 77 Atlas V launches from Vandenberg and Cape Canaveral, Fla.