You forgot to mention our lovely Ottawa Valley humidity. While this summer has been relatively dry (27 only feels 31 today), we usually get a few stifling weeks in either July or August (sometimes both) where the highs are mid 30s+ and the humidity 90+%. Ugh.

My wife and I went to the US southwest a few years ago. When we left LA it was a bearable 115F (dry as a bone). We got home to 21C and had to start the AC because we couldn't breathe - it took us a day or so to reacclimatize, it was so humid.

You also left out how windy our Ottawa winters can be, and how much snow we can get (cf, e.g., http://ottawa.weatherstats.ca/metrics/snow.html)

There's a reason we invented humidex and issue so many wind chill warnings.

(Ottawa is one of the most beautiful cities ever, and was recently ranked fourth most livable city in Canada by MoneySense, after Calgary and two suburbs of Edmonton. Not bad for an urban area of about ~1M with sticky hot summers, frigidly cold winters, and some of the most aggressive drivers ever (we really do need to chill). It makes up for these with a splendid natural setting, ready access to nature and the arts, and only one major source of pollution, the car.)