Icicles hang down from the upper deck of Coors Field...

Icicles hang down from the upper deck of Coors Field before a baseball game between the Colorado Rockies and the New York Mets, Saturday, April 17, 2021, in Denver, the day after a spring snow storm. (AP Photo/David Zalubowski) Credit: AP

DENVER — As the old baseball saying goes: Some days you win, some days you lose and some days it snows — even in mid-to-late May, apparently.

A spring snowstorm caused the postponement of the Mets’ series opener with the Rockies on Friday night. It was rescheduled as part of a split-admission doubleheader on Saturday, with first pitches set for 3:10 p.m. and 8:40 p.m. ET.

That will be the Mets’ fourth doubleheader of the month (and fifth of the season).

Incredibly, this was the second season in a row — and the fourth time in a decade — that the Mets had a game pushed back because Denver got hit with late snow while they were in town. Last year, it was mid-April, and although the conditions required the Rockies to break out their miniature snowplows to get the field in shape, the teams managed to play the complete three-game set. In 2013, they had two of three games snowed out in April, requiring a return trip that June.

This postponement alone might not further mess with the Mets’ pitching plans, which already have been wrecked by recent injuries to Max Scherzer (left oblique strain) and Tylor Megill (right biceps tendinitis). Carlos Carrasco will start the first game Saturday, Trevor Williams (on short rest) the second game.

David Peterson traveled with the Mets on Thursday but has not been added to the active roster. He attended Regis Jesuit High in nearby Aurora, and if he gets into a game this weekend, it will be his first at Coors Field. For now, however, he looks like a primary option to start Monday in San Francisco in place of Scherzer.

Whether the Mets (26-14) will be so fortunate as to play all three games is not clear. The forecast called for four to six inches of snow, which is expected to fall through Saturday morning. It’s expected to be 40 degrees when the Mets and Rockies start their first game.

Another postponement Saturday would be deeply inconvenient for the Mets, who would have to come back to Coors Field on a would-be off day for a makeup game. But the teams’ schedules happen to give them options, if necessary.

Perhaps the best: June 13, which is supposed to be the Mets’ requisite day off following a West Coast trip (which will take them to Los Angeles, San Diego and Anaheim). The Rockies (18-19) will be about to start a homestand.

Another possibility: Sept. 26, which also is supposed to be the Mets’ requisite day off following a West Coast trip (this time to Oakland). The Rockies will be just wrapping up a homestand.

The less attractive options are Sept. 8, when the Mets will be between series in Pittsburgh and Miami, or in August in New York. The Rockies will visit Citi Field Aug. 25-28, and the teams could mix in an extra game as part of a doubleheader or their shared Aug. 29 day off, with Colorado playing as the home team despite being on the road.

MLB almost never does that, but it did happen during the fanless, pandemic-shortened 2020 season, so maybe it would be considered under extenuating circumstances.

Earlier this month, MLB allowed the Tigers and Athletics to play a “home” game each during a doubleheader as they sought to make up an early-season series postponed by the lockout.

Cahill a depth signing

The Mets signed veteran righthander Trevor Cahill to a minor-league contract, they revealed Thursday. He is not close to being ready for the majors, and it wasn’t a reaction to Scherzer getting hurt. It does give the team an extra bit of depth, albeit in the form of a pitcher who hasn’t been very good most of the last few years. Cahill, 34, had a 6.57 ERA in nine games (37 innings) for the Pirates last season but was much better (3.24 ERA in 25 innings) for the Giants in 2020.