I am a meteorologist at the Natl Weather Service in Grand Forks ND. I was fascinated by weather at a very very early age. I would play with cars and pretend I was driving in snow (even to the point of using baby powder to put on the road track to simulate snow). I would also love to draw maps and put weather symbols on them and draw fronts. I grew up just a bit before the weather channel (it came out while I was in high school in the early 80s)..but I did watch all the local TV weather people and A.M. Weather which was on early in the day on PBS here in the states.
Anyway....this is an interest I carried to this day. But on the other hand I have talked to young kids at that age and there were fascinated by weather for a few years but later turned to something else, such as hockey, which most boys in my area get into.
Like any hobby, if you will, encourage him to read books on weather at the library or order some tornado videos. There are weather kits out there (mostly on-line) that one can set up easily and the person goes out and reads the temperature and rainfall daily and puts it in his own weather log. I had one for many years and loved doing it. Also there are cloud charts available so he can study the different type of clouds.
I see you are in Canada, and check with Evironment Canada website for info on kids activities. The point being, instead of sitting and watching TV all the time let him get out and explore the weather my describing the type of clouds he sees or taking his own observations.
Here are some ideas from Ev Canada website for Ontario
Environment Canada - Weather and Meteorology - Publications
Environment Canada Kids Page (http://www.on.ec.gc.ca/kids_e.html - broken link)
Weather-Pathfinder: KidsSpace: Toronto Public Library