You could use the site for weather in the United States.  They also have international locations.  Current weather at [Watsonville,CA, US|], current weather in [Kabul,AF|]  Provides a lot more data then just an image.  Maybe use the station as an input for the plugin.

After checking, they offer an XML interface to the public.  It should be relatively easy to build a plugin with this.

The easy way is to use the [Rss Viewer Plugin] that does the RSS work for you.  Just insert 
  detail='1' ttl='120' date='1'}]
in the page to get current observations.  -- [Foster Schucker]