The Golden Bears looked like they were on their way to an easy victory up 31-7 in the third quarter. Instead, they had to sweat this one out.
Northwestern got two touchdowns in a 25-second span late in the third to pull within 10. Jack Mitchell added a 24-yard field goal with 5:18 left in the game to make it 31-24, and the Wildcats were threatening to score again when Jefferson came up big.
With Northwestern on the California 27, he sacked Trevor Siemian for an 11-yard loss. On the next play, he picked off a tipped pass that was intended for Pierre Youngblood-Ary at the 15, and the Golden Bears came away with the win after dropping 16 straight to FBS opponents.
The late rally aside, it was a rough afternoon for Northwestern.
The Wildcats are trying to steer attention toward their play after being engulfed by the unionization debate with former quarterback Kain Colter leading the movement, and this was not what they had in mind.
Coming off a 5-7 season, they couldn't slow Cal's up-tempo offense or get anything going when they had the ball.
Goff, who threw for more than 3,500 yards as a freshman, was 21 of 34 with an interception.
Trevor Davis caught a 76-yard touchdown. California racked up 414 yards to come away with the win after going 1-11 in coach Sonny Dykes' first season.
Northwestern's Trevor Siemian, who shared the quarterback job with Colter the past two years, threw for 229 yards.
Cameron Dickerson had a 54-yard touchdown reception, but the Wildcats came up short after making things interesting down the stretch. It started with that 25-second stretch late in the third, when Justin Jackson scored on a 7-yard run and Siemian hauled in a 17-yard pass off a flea-flicker from Jayme Taylor following an interception by Collin Ellis. That made it 31-21 with just over 2 minutes left in the third quarter. Until then, Northwestern got dominated.
Cal asserted itself right from the start, going 79 yards for a touchdown on the game's opening possession.
Goff, who threw for 450 yards and two scores in last year's loss to the Wildcats, hit Bryce Treggs on fourth down at the 1 to make it 7-0. And things just mounted from there.
Northwestern was then threatening to score when Warren Long got stopped on fourth-and-1 at the Cal 22, and the Golden Bears responded with another touchdown.
This time, Goff hit a leaping Kenny Lawler in the end zone for a 7-yarder that made it a 14-point game, and the Golden Bears continued to pour it on.
Cal started its next possession early in the second quarter on the Northwestern 29 after a short punt out of the end zone by Chris Gradone off a bounced snap. That led to a 20-yard field goal by James Langford to bump the lead to 17-0.
Northwestern finally broke through when Siemian connected with Dickerson on a short slant for a 54-yard touchdown with 6:26 left in the half. But any thoughts of a rally got squashed on the next play from scrimmage, when Goff found an open Davis for a 76-yard touchdown, making it 24-7.