I'm not really certain about eastern Canada, but in Calgary the seasons are something like:

  Spring: Mid-March til Mid-May.  Snow goes away.  Then it
          comes back.  Then it goes away.  Then it comes
          back.  Then it goes away.
  Summer: Mid-May til early September (with luck) or late-
          August (without it).  Mostly warm, usually dry.
          Punctuated by hailstorms.  Once every few years
          punctuated with a smallish snow storm.
  Fall: Early September til late October.  Stuff cools down.
        Frost is common.  Occasional hail or freezing rain.
  Winter: Late October til mid-March.  October-til-Christmas
          swings back and forth between (very) cold streaks
          and stereotypically fall-ish weather.  January to
          March is mostly just cold and snowy and icy.

Bear in mind that the climate really only gets worse the further east you go, culminating in the maritimes - where winters of five-foot snow alternate with summers of hurricanes. :P

No, the one between `Spring' and `Fall' is called `Construction'.

I'm from Montreal and currently that's now year long.

It's pothole season here.. That's how we know it's spring!

We call it "Spring plowing" in Iowa. Or "Fall Plowing", whatever works.

Edmonton's like Calgary, but with all the cold periods extended :D.

http://www.whitemagicsoftware.com/software/climate/master.sh... ;-)