Gerardo64 at the Google Earth BBS has created a file containing global overlays of several datasets available from the NOAA Environmental Visualization Laboratory. The data used to create the maps is collected by satellites and is updated every day.
The following layers are included.
Land Surface Temperature Sea Surface Temperature Snow [...]
The ac network weather blog has created a Google Earth layer to display current METAR weather conditions from NOAA for many regions throughout the Earth. Just find the location of interest and click on the dot. The pop-up balloon contains a link to a website with additional information about the station/airport.
The NASA Earth Observations website has dozens of layers of global scientific data formatted for viewing with Google Earth.
The data is grouped into Ocean, Atmosphere, Energy, Land and Life categories. The layers are too numerous to list, but they include:
Sea Surface Temperature Chlorophyll Concentration (MODIS) Snow Cover & Sea Ice Extent [...]
For those of you that are dreaming for a White Christmas, here are a few maps to help predict whether your dream will come true or not.
There are three maps included in this set of overlays that show the probability of having a white Christmas in the United States with 1-inch, 5-inches, [...]
The Cooperative Institute of Meteorological Satellite Studies at the University of Wisconsin-Madison Space Science and Engineering Center (CIMSS-SSEC) has created a huge set of weather related overlays that can be viewed in Google Earth.
Their program is focused on tropical cyclones, but they also have a large amount of satellite and other data [...]
The Advanced Very High Resolution Radiometer (AVHRR) sensor collects cloud and other data from several satellites orbiting the Earth. The University of Wisconsin has created an archive of AVHRR false color imagery dating back to 2007. In addition, they have created a network link that updates automatically every day with the most recent satellite [...]
The MODIS sensor on the Aqua and Terra satellites capture amazingly detailed natural color imagery every day from all over the Earth. The imagery is detailed enough that you can easily see cloud formations, snow coverage, smoke from large fires, etc, for the entire US. And the best part is the imagery from these [...]
AWEKAS (Automated Weather Maps) is a network of weather stations located throughout the world. Click on a placemark to see weather conditions (temperature, pressure, etc.) at that location. Some locations also have live webcams.
The data is provided in several different languages.