Ferrari’s Carlos Sainz was third fastest on a drying track and seven times world champion Lewis Hamilton fourth for Mercedes on a weekend dominated by talk of ‘porpoising’, or bouncing, cars.
“I still expect it not to be a straightforward race,” said Verstappen after the Dutch driver’s second pole in nine races this season. “But today with the tricky conditions we stayed calm and didn’t make mistakes.
“I’m super happy to get pole position and to be back in Montreal.”
His qualifying time of one minute 21.299 seconds was 0.645 faster than Alonso’s best.
Today’s race at the Circuit Gilles Villeneuve will be the first in Canada since 2019 and the start of the Covid-19 pandemic, and it is forecast to take place in sunny and dry conditions.
Verstappen has won four of the last five races and leads team mate Sergio Perez by 21 points, with Ferrari’s Charles Leclerc a further 13 behind.
Double world champion Alonso, the oldest man on the grid at 40, had been fastest in the day’s final practice and said with a grin that he planned to attack Verstappen into the first corner.
Leclerc, on pole in the last four races, will start at the back after collecting engine penalties.
Haas’s Kevin Magnussen qualified fifth with team mate Mick Schumacher a career highest sixth. Alpine’s Esteban Ocon lines up seventh and Mercedes’ George Russell eighth.
“It’s something I can build on and grow from. I always loved racing in the wet conditions. On a track like this, there’s big potential for drivers showing what they can do,” said Schumacher.
McLaren’s Daniel Ricciardo qualified ninth and Chinese rookie Zhou Guanyu lines up 10th for Alfa Romeo. The Chinese driver was making his first ever Q3 appearance, but will be investigated after the session for an infringement at Turn 14.
Qualifying was halted in the second phase when Perez went straight into the Tecpro barrier between turns three and four and could not reverse out.
The car had to be craned off and the barriers repaired before the session resumed.
Perez qualified 13th, one place ahead of McLaren’s Lando Norris who failed to set a time in the second stage after reporting an issue with the power unit that the team were unable to fix.
Williams’ Alex Albon had also gone into the barriers at turn six earlier but was able to continue, returning to the pits for a new front wing and eventually qualifying 12th.
Valtteri Bottas was 11th, ahead of Albon.
Leclerc was P15, but will fall back with his penalty, promoting Alpha Tauri’s Pierre Gasly, Aston Martin’s four times world champion Sebastian Vettel and his teammate Lance Stroll and Williams’ Nicholas Latifi, who all dropped out in Q1.
Yuki Tsunoda will bring up the rear of the field, having also taken engine penalties for power unit changes.
Vettel and Canadian Stroll failed to progress from the wet opening phase, with Verstappen fastest, after they had raised hopes in final practice.
Latifi completed a miserable afternoon for Canadian drivers in 19th place, although he will move up a slot after Leclerc’s demotion.