Eeli Tolvanen made it 2-0 at 7:23 with a wrist shot from the left circle on the power play.
Grimaldi scored 16 seconds later to extend the lead to 3-0, shooting from a sharp angle along the goal line after he forced a turnover by Greiss. He then completed the hat trick to make it 4-0 at 8:08 when he shot into an open net off a centering pass from Haula.
The hat trick in 2:34 was the fastest in Predators history.
"I think for me personally, I can be pretty pessimistic at times and wonder if the puck is ever going to go in again," Grimaldi said. "But I have a lot of good people surrounding me in my life, my family and my friends, that were just through this last month or two trying to keep me on track. As long as my effort is there, as long as I'm doing the best that I can to help our team win, it doesn't really matter if I'm scoring. As long as the team is winning games, that's what my focus needs to be on all the time."