Xbox Media Center has a built-in weather feature. You are able to display the Weather.Com forecast for three different locations from around the world. You can configure your locations and whether the forecast is displayed in Metric or Standard increments in the Weather Settings.
To navigate between the 3 different locations highlight the small arrows and press the A button on the controller (or the Select button on the remote). After that highlight “Refresh” and you should see the weather forecast on screen.
You can configure up to 3 cities to display on this screen. The settings are located in the 'Settings' tab off the home page.
For more details about configuring My Weather see the Weather Settings page.