I was just checking on an entry on my Dashboard on Garmin Connect, and when I clicked through on the link to look at it in detail I noticed it now has weather information! It doesn't go back as far as April 2012 (where I spot checked), but at least December and January are covered. Motion Based used to do this, and I'm glad that weather has finally arrived on Garmin Connect.
I noticed this too over the weekend. Very happy to see this now included. I used to have this on Nike+ before upgrading to a Garmin, and really liked it.
Did you need to do anything, or did Garmin Connect just finally start showing the info for you? I don't see it, but I am not sure if I simply am not waiting long enough.