Maybe Jon Niese should do a rain dance before every start.
The lefty pitched through what at times was a steady downpour and delivered his finest performance of the season in the Mets’ 3-0 win over the Nationals last night at a drenched Citi Field.
And he was at his best when the conditions were awful, getting out of a bases-loaded jam in the seventh.
“I couldn’t take him out,” manager Terry Collins said. “He earned the right [to finish the inning].”
After getting the first two outs, Niese surrendered a double, a walk and then an infield single to third to bring up leadoff hitter Roger Bernadina. Niese fell behind 3-0 before getting back to a full count and then got Bernadina to ground to Daniel Murphy at first.
“I was excited to finish that inning,” Niese said. “It meant a lot, especially with the weather and all the variables.”
One night after postponing a game even though no rain ever fell, the Mets slogged through their fifth win in seven games. And though the sky opened almost once an inning, the game was never stopped — though parts of the left side of the infield looked like small lakes by the latter innings.
“I’ve never pitched in anything like that,” Niese said. “That’s the wettest I’ve ever been pitching. Every ball the umpire gave me was soaking wet and I kept trading them out till I got a dry one, and even those were still kind of wet.”
Crew chief Bill Miller had no comment afterward on the decision to play through the soggy conditions, but Collins said he asked him about it in the eighth.
“I told him it was starting to pile up now,” Collins said. “But we got through it.”
Niese wasn’t sure they would.
“I was surprised,” said Niese, who said the mound held up fairly well. “I didn’t know what the heck we were doing out there.”
He and Ronny Paulino stuck mainly to Niese’s fastball, since that was the easiest pitch for him to control. And Justin Turner provided enough offense for Niese.
The Mets took a 1-0 lead in the first when Turner doubled Jose Reyes to third. Reyes later scored on Jason Bay’s sacrifice fly to left.
Turner doubled again in the sixth, this time scoring Scott Hairston and Reyes, who had been intentionally walked prior to Turner.
It helped make up for the fact that the Mets were 1-for-12 with runners in scoring position and left 11 men on base.
Turner’s double gave Niese (3-4) some breathing room. He lasted seven innings and struck out seven, both matching season-highs as the Mets got their first shutout of the year. Their last one came on Sept. 13 last year in Pittsburgh.
Though the Mets need inexperienced players such as Turner and Ruben Tejada — who made his season debut — to do well if they have any chance without the injured Ike Davis and David Wright, they’re even more reliant on getting strong showings like the one Niese gave them last night.
“With our lineup shaken up we really have to pitch,” Collins said.
Niese will have to play a significant part in that and Collins thought last night was a critical step for him.
“This was a sign of growth,” Collins said. “And as we go into the summer, it shows he can pitch out of a jam.”
As well as in a monsoon.
— Additional reporting by Brian Lewis.
dan.martin@nypost.com