I was looking around and found (what I think to be) a nice plasma weather applet.  
Here is the copr:  https://copr.fedorainfracloud.org/coprs/gbcox/forefront/build/442368/

It's under review here:
https://bugzilla.redhat.com/show_bug.cgi?id=1367971

The widget displays info either horizontally, vertically or in a compact mode.  I prefer compact.
Hover over the icon gives you a summary popup... if you left click, you get a nice meteogram display.  It uses the yr.no service - which seems fairly comprehensive.

Have fun!