Weather Spider

Use this plugin to place current weather and/or weather forecast (up to 5 days) from weatherbug.com within your blog and sidebar. Options to show or hide both the current weather and weather forecast. If displaying forecast, choose to display 3, 4, or 5 day forecasts. Comes with a handy widget for your sidebars and an easy-to-use short code for your Pages and Posts.

This plugin requires an API Key which can be obtained for free from http://developer.weatherbug.com/. This plugin will cache the weather data for 15 minutes and uses Ajax to build the weather forecast using semantic markup.

http://www.leonamarant.com/2012/02/07/weather-spider-wordpress-plugin/