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!