Hope you enjoyed sleeping in on a Friday. I poked around wolframalpha and there isn't a way to get all monthly temperatures in a single table.
What I would do is query something like "Toronto monthly mean temperature 2010" and print out the resulting website.
Simply query each month and get the average temperatures e.g. query "Toronto mean temperature January 2010" and average the high and low. Use that value. Please include a table that shows the numbers you are using.
Have a great weekend. You too grade 10's.