Kevin's Blog

Weather terms and forecasts are part of our daily lives. It is impossible to go an entire day and not hear a weather term on the radio or television, or use one of your own after sensing the temperature, moisture, winds or the skies above you. Weather forecasts and weather words are commonplace, and as such, provide opportunities for their use in clandestine ways.

Historians agree that World War II was primarily responsible for the proliferation of code names. As you can imagine, because weather terms were heard so often in daily activities, they became great code words. Weather terms were used as code by all of the warring governments in WWII, although much less by Germany than by the U.S. The German method of coding usually combined a color with a noun. Because of the use of colors, the Germans called this list of words the Rainbow Codes.

Care to guess the codename used by the U.S. and Great Britain to describe their plans against the Axis powers? It was "Rainbow" of course! The use of rainbow as a code word tells me that code breakers on both sides learned very quickly that weather words and colors were being used as coded information.

In January 1945, the Germans used Nord Wind (north wind) as the codeword for their counterattack in Alsace against the U.S. Seventh Army. Care to guess which direction they attacked from? Even a weather forecaster like me might have guessed right on that one!

Code words used by the Americans in WWII included "Atmosphere," "Fogbound," "Snowball," "Frostbite," and "Nimbus." You can probably determine by the tame nature of these words that none of them involved invasions. But what about "Thunder," "Tornado," and "Cyclone?" You have correctly surmised that each of these code words involved an invasion. In other words, a little meteorological knowledge would have gone a long way in helping break codes on both the Allied and Axis sides.

This past Sunday we observed the 67th anniversary of the bombing of Pearl Harbor. As with any military exercise in our world's history, weather was a critical component. In this case however, it is the weather phrase "East wind, rain" that is the most well known. This coded message (part of the Japanese "wind codes") was supposedly used to notify Japanese diplomats in the U.S. to begin destroying documents and encoding machines because the bombing of a U.S. installation was imminent.

"East Wind, Rain" is a popular Pearl Harbor book title in both the U.S. and Japan.

The "wind codes" have been thoroughly studied by historians in an attempt to determine whether the U.S. Government had evidence of the Japanese attack beforehand.

Sixty-seven years ago today, December 8, 1941, Congress passed a declaration of war thus entering the U.S. into WWII. As part of this week's observance, we have provided a peek at the original "wind code" documents from 19 November 1941. These documents have been made available by the National Security Agency's Center for Cryptologic History and the New York Times.

If you have any questions about the use of weather words as codes, or can think of how weather words have been used in other military conflicts, share them here!

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