MetaWeather is a weather aggregation site that describes itself as "An automated weather data aggregator that takes the weather predictions from various forecasters and calculates the most likely outcome." Oddly enough I was just chatting with someone about how a "Metacritic for weather information" would be a good idea and it could be called "MetaWeather." So I checked the URL and sure enough, there are no new ideas under the sun.
Disappointed that I hadn't come up with the idea first, but excited that it existed, I checked it out. It's got a definite "side-project" look to it and has some rendering issues in the three browsers I tried it in (IE7, FF2, and Opera). For instance, it shows temperature ranges on a bar graph and if the range is small (for instance between -12 and -9 the two numbers are smashed on top of each other.)
The sources for Chicago listed are Weather.com Homepage, Weather.com weather for Chicago, BBC Homepage, BBC Weather for Chicago, Weather Underground Homepage, and Weather Underground weather for Chicago. I'm not sure why it lists all those weather site home pages, which don't list anything about specific cities. Also, I'd rather see Accuweather and The National Weather Service incorporated. However this may be an API issue.
Again, this looks like a side project and maybe that's all it is. Or an experiment. But I'd like to see a full-scale version of a meta-weather site at some point tricked out with more features and a little more polish. After a quick check of all the weather sites metaweather.com uses and the ones I mentioned, I'm amazed at the disparity. Averaging all this data in a slick way could be very helpful.
So while I really like the idea and initiative the Metaweather folks have shown, I look forward to its maturity even more.