Late summer and early fall (August through to the end of September) are probably the warmest and the most visually stunning months to be on the prairies. As the old farmers said; "You can have the mountains they only block the view".
Now winter on the Prairies is a different story. It can be nasty cold like today while I'm writing this. It is November and -30C with the wind chill. But there are some perks as well. Since the sun doesn't break the horizon until after 8:00 am I can sleep in a bit and still get a nice early am shot. To do this in the summer I have to be up at 3:00 am for the 4:00 am sunrise. Another big plus is that since we are as far north as we are the sun never gets to more than 13 degrees above the horizon so that magic morning and late afternoon light is a photographer's dream. This is what I mean. Look below.