I cannot add widget from url http://www.silverstripe.org/widgets/manage/add
for error: Security token doesn't match, possible CSRF attack.

So I'm put it here.

Weather Widget 0.0.1 for SilverStripe 3.x

Google silently kills popular API, breaks weather apps everywhere, so you need to sign up here http://www.wunderground.com/weather/api/?ref=twc
to obtain License Key and Partner ID.
To find location ID go to http://www.weather.com/forecast, e.g.: Kosice, Slovakia.
You'll see inn address bar
http://www.weather.com/weather/today/Kosice+LOXX0003:1:LO, so location ID is LOXX0003.
Then you can lookup anywhere in the world and provide wether for it.

Installation:
Read carefully https://github.com/silverstripe/silverstripe-widgets.
Make sure you have enabled widgets first to use (http://doc.silverstripe.org/widgets?s[]=widget#adding_widgets_to_other_pages)

1. extract this to your SilverStripe root directory widget_weather
2. run "dev/build?flush=all"
3. visit your page and drag and drop the widget to the right

I'm using https://github.com/twitter/bootstrap/, so template assumes bootstrap is loaded (jquery, js, css), becouse it uses bootstrap accordion.
You can rewrite template to your needs.

Source: https://github.com/JStika/weather

I just tried submitting a widget to the widget submit page and the form worked for me. I know I've seen this error occur on some of my sites when I've accidentally used static publisher to cache a form page that I shouldn't have.