In an effort to aid users who are planning trips, outdoor activities, or who just want to check weather conditions and forecasts anywhere in the world, Google Maps  has introduced an optional weather layer. Weather data for this feature is provided by Weather.com , and is enhanced by cloud imagery from the U.S. Naval Research Laboratory .
To activate it, check Weather in the widgets list in the upper right corner of a Google Map.
Current weather conditions are displayed when the cursor is held over a weather icon.
Click the icon to receive a four day forecast for that location, along with more detailed information on current conditions (humidity, wind speed and direction, etc.).
The information panel reveals weather from the surrounding area, along with options to display information in different formats (Show/Hide panel control seen below).
Wind speeds can be displayed in miles per hour (mph), kilometers per hour (km/h), or meters per second (m/s), and temperatures in either Fahrenheit or Celsius. More detailed weather information can be obtained at the Weather.com link, appearing at the bottom of the panel.
Zooming out reveals cloud coverage; a feature controlled by a Show/Hide clouds link in the panel.
Combining weather with Google Maps is a great idea, but weather forecasts are typically about as accurate as predictions by psychics and economists, so if your next trip includes outdoor activities based on a sunny forecast, you may still want to pack an umbrella.