Monahan scored his 26th and 27th goals in his first career three-point game as Calgary rode a four-goal first period to a 6-3 win over the Toronto Maple Leafs.
The 20-year-old forward has 10 goals on 24 shots in his last 13 games to move into a tie with Patrick Kane and Zach Parise for 11th in the NHL in goals.
Linemates Jiri Hudler and Johnny Gaudreau each pitched in with one goal and two assists. The Flames top line has been scorching hot lately with each player on a six-game point streak— combining for 16 goals and 30 points over that span.
"It's quite the chemistry they have between the three of them. Jiri's leading the pack and the two kids are following," said Flames coach Bob Hartley. "They're unbelievable. They're fun to coach and they're fun to watch. They're moving so well, they're creative and they're responsible."
Gaudreau has 19 goals and 53 points, moving him into a tie for the rookie scoring lead with Nashville's Filip Forsberg.
"For me, it's the chemistry," said Gaudreau, 21. "When you get to play with a player or a few players throughout the whole season, you just feel really comfortable with them on and off the ice. You learn more and more about them and where they're going to be at on the ice."
A 5-0-1 record in their last six games— all without captain Mark Giordano, who is lost for the season with a torn biceps tendon— moves the surging Flames into second place in the Pacific Division, one point up on Vancouver. The Canucks have one game in hand.
Calgary (38-25-5) also got goals from Drew Shore and Mikael Backlund.
Richard Panik and David Booth, with a pair, scored for Toronto (27-36-6). The Leafs fall to 1-16-2 on the road in the calendar year.
"I'm not going to sit here and make excuses. Bottom line is we made more mistakes than them and they capitalized," said Leafs captain Dion Phaneuf. "There's no sugar-coating it or beating around it. It's pretty evident what happened."
With the Flames leading 2-1 halfway through the first period, a potential momentum-changing moment in the game came in the form of a five-minute major to Lance Bouma for a knee-on-knee hit on rookie Brandon Kozun.
It did turn out to be key moment, but not as one might expect.
In a three minute span, Backlund and Monahan scored short-handed breakaway goals to make it 4-1 and fire up the raucous sell-out crowd of 19,289.
"It was an awful start," said Leafs coach Peter Horachek. "We had two scoring chances the whole first period, we had seven minutes in power plays and they got two short-handed goals. They outworked us the whole period. Everything that happened to us, we did it to ourselves."
The Flames opened up a four-goal cushion 1:29 into the second when Monahan scored again. Booth got one back for Toronto at 4:56 but Hudler's power play goal at 8:16 restored the four-goal lead.
"Everyone's contributing offensively right now," said Gaudreau. "Each game is crucial, we need every single point if you look at the playoff race and we came out flying."
In the Flames net, Jonas Hiller had 25 stops to improve to 21-17-4. Reimer has 22 saves for Toronto. His record falls to 7-15-0.
Notes: Backlund extended his point streak to a career-best seven games (3-4-7)... The Flames are 13 games above .500 for the first time since January 5, 2010... During this 19-game road stretch for the Leafs dating back to the start of January, Toronto has only led for 25:43 out of 1,145 minutes... Nazem Kadri did not play for Toronto. It was the third game he's missed after being suspended by the team for disciplinary reasons.