Theme Egg

This is Weather Forecast widget plugin, You can add widget by installing this plugin. 
After Installing this plugin go to Appearence>>Widget and add widget to your sidebar.

Weather Forecast

This is Weather Forecast widget plugin, You can add widget by installing this plugin.

WP-Tlon

WP World Weather Online displays a Weather Widget in your sidebar or on single pages/posts
<h4>Features</h4>
<ul>
<li>show today’s weather</li>
<li>show weather forecast for next 3 days</li>
<li>choose between Celsius or Fahrenheit</li>
<li>choose different color themes</li>
<li>supports shortcodes for single pages or posts</li>
<li>comes with predefined CSS style if themes are not enough for you</li>
<li>valid XHTML output</li>
</ul>
In this version some small bugs have been removed plus some functionality added.
<h3>Credits</h3>
Copyright 2014 by Alex Kalinovski
This program is free software; you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by 
the Free Software Foundation; either version 2 of the License, or 
(at your option) any later version.
This program is distributed in the hope that it will be useful, 
but WITHOUT ANY WARRANTY; without even the implied warranty of 
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
GNU General Public License for more details.
You should have received a copy of the GNU General Public License 
along with this program; if not, write to the Free Software 
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

WP World Weather Online

Displays a weather widget via widget or shortcode using the World Weather Online service API. * show today's weather * show weather forecast for  …

Weather Forecast vs WP World Weather Online