Yes, there are multiple flights from Lester B. Pearson Intl to Mae Fah Luang International for under C$ 2,272. The cheapest flight booked recently is on Multiple Airlines for just C$ 2,224, but on average you can expect to pay C$ 6,885.
There are no direct flights from Lester B. Pearson Intl to Mae Fah Luang International, but Cheapflights can provide you with all the information you need to find the fastest route with the fewest stops.
When travelling, it's generally smart to pack in preparation for rain or any other conditions that may arise. The rainfall in Lester B. Pearson Intl is roughly greater than that of Chiang Rai. You can assume this to be the case over the next 20 days.
With an average temperature of 35 °C, peak weather can be found in April. As a traveller, expect to see changes in flight prices during that period. The temperatures in Chiang Rai are hotter than in Lester B. Pearson Intl.