The Cubs said goodbye to winter Sunday at Wrigley Field, hoping the transition to summerlike temperatures Monday will set them on a prolonged run.

They’ve won four straight and nine of their last 13 after sweeping the Brewers with a 2-0 win Sunday, and we’re still waiting for the offense to break out.

For now the Cubs will take what they’re given. A win’s a win, so if the pitching is going to carry them for now, that’s fine.

Tyler Chatwood continued the Cubs starters’ mastery over the Brewers, throwing seven shutout innings and allowing only two hits. He started by walking Lorenzo Cain on four pitches but settled in after a mound meeting with catcher Willson Contreras three batters in.

“Trust your stuff, trust (that) we’re going to have a good day,” Chatwood recalled Contreras saying. “After that I feel like I was able to pound the zone pretty well.”

The Cubs tossed three shutouts in the series and allowed only one earned run. They’ve won seven of eight over the Brewers and posted five shutouts against them in April. It was the first time in history they’ve accomplished that in a calendar month and the first time they’ve done it to one team in a season since shutting out the Mets five times in 1973.

“I knew it was pretty good, but that’s pretty astonishing,” manager Joe Maddon said.

Even more astonishing is the fact the Cubs hadn’t won four straight while scoring three or fewer runs in a game since at least 1908. The starters did not allow an earned run in the sweep and have a combined 0.90 ERA over their last six starts, limiting opposing batters to a .145 average.

Of course, you’d still like to see Anthony Rizzo and Addison Russell break out, for Ian Happ to cut down on his strikeouts and for Contreras to improve on his .130 average with runners in scoring position.

When those things happen, as they should once the weather heats up, the Cubs could have the best-hitting lineup in the National League.

So far it’s been a virtual rerun of last April for the Cubs offense, which means they’ve managed to keep their heads above water without being dominant.

At the end of last April, the Cubs had a slash line of .255/.339/.416 and averaged 5.1 runs per game while going 13-11. After Sunday’s win, they had a slash line of .254/.336/.416 and averaged 5.2 runs per game with a 15-10 record.

In other words, it’s basically the same offensive start, despite playing in brutally cold conditions at home and going without Rizzo, Ben Zobrist and Kris Bryant for stretches.

“The way we’ve played over the first three weeks, considering the weather and the delays and the cancellations, right around .500 is a really good record for what we went through,” closer Brandon Morrow said. “With the weather warming up a little bit, I think we’re going to play better. Guys are going to start feeling better and just get on a roll. And I think we’ve started that a little bit.”

Maddon generally likes to shake up his lineup, which is a manager’s prerogative. But recently he has stuck with right-handed-hitting Albert Almora Jr. and Javier Baez at the top against right-handers, seeing vast improvement from both, even though their 11-game hitting streaks both ended Sunday.

“Now they’ll still chase on occasion, which you’ve got to expect,” Maddon said. “But for the most part, the count gets deeper, you’re not seeing that really big, all-out hack. You’re seeing the ball go the other way.”

Jon Lester takes the hill Monday night when the Rockies come to town. Temperatures are expected to climb into the 60s, ushering in the first stretch of warm weather at home this season.

Now we’ll find out whether they’re the boys of summer again.