LOS ANGELES — Almost immediately after Arizona pitcher Danielle O’Toole threw her last pitch of the game Sunday, it started raining at Easton Stadium.

It was a chilly and windy weekend, and for the Wildcats it was mostly gloomy. Especially with the way Arizona played in its first two games against 12th-ranked UCLA, when UA was shut out in two straight games by its biggest rival.

Sunday, the third-ranked Wildcats were back in good spirits. That last O’Toole pitch completed a strikeout and an Arizona 7-2 win. The senior pitcher met the horde of Arizona’s entire roster at the first base line for a postgame celebration.

With the win, Arizona won the Pac-12 regular-season championship, its first conference title since 2007 and the 11th in program history.

“I’m really happy for the kids,” said UA coach Mike Candrea. “It’s been a tough weekend, and to finish it off this way and clinch the Pac-12, it’s a huge stepping stone. I didn’t want to downplay it because it is important. It’s a very prestigious award to win this conference, and they did a hell of a job this year to make it happen. I’m glad it happened today.”

After the game, the Wildcats were presented with a Pac-12 championship trophy, along with T-shirts and hats that read “Pac-12 Champions.” Had the Wildcats lost on Sunday, the possibility loomed that Utah or Oregon, with three wins next weekend, could have stolen the title away from Tucson. But that’s a what-if the Wildcats won’t have to deal with.

“It’s pretty cool,” said O’Toole, who improved to 27-4 with the win. “I’m glad that we came out today the way we did.”

Added outfielder Mandie Perez, who went 3 for 4 and scored two runs: “It’s just awesome. I’m just so happy. I’m just really, really proud of everybody. Who cares if it was bumpy (against UCLA) the first two days? We did it when it counts.”

O’Toole was impressive against the Bruins — outside of a sixth inning Delaney Spaulding solo home run, UCLA only managed three hits and one run, while O’Toole struck out six and walked one — but it was the reawakening of Arizona’s bats that guided the Wildcats to its dominant regular season-ending win.

The Wildcats led the game off with three straight hits, an infield single from Perez, followed by two base hits to the outfield from Mo Mercado and Katiyana Mauga.

Then freshman Jessie Harper stepped up to the plate, and on Paige McDuffee’s sixth pitch to her, she launched a grand slam to left field, scoring Arizona’s first runs of the weekend.

It was Harper’s 19th home run of the season.