Weather Conditions – December 7, 1941

Weather Watch

December 7 marks the 75th anniversary of the Japanese attack on Pearl Harbor. It was the event in our history that President Franklin Roosevelt described as a “day that will live in infamy,” and catapulted the U.S. into WWII.

There were many factors that contributed to the level of destruction of the Japanese air raid that day including the decision to move the US Naval Pacific Fleet from San Diego to Pearl Harbor just a year earlier, and of all things, weather.

Pearl Harbor was logistically a better target than San Diego for the Japanese and the weather in and around the Hawaiian Islands is normally conducive to flight unless there is a major weather system such as a hurricane, which is rare. The area does, however, receive a lot of rain, with an average of 12.27” in December, but rain showers normally start in the afternoon and never last long.

History records that naval officials opposed the move because they thought it would unnecessarily expose the fleet to Japan’s naval strength, but President Roosevelt considered the move a necessary countermeasure to the growing Japanese threat.

The morning of the attack, temperatures were in the low 70s (average December temperatures for Pearl Harbor range from  a low of 64 to a high of 78) with mostly clear skies and just a few scattered cumulus clouds over the mountainous areas. These conditions allowed the Japanese to execute their aerial attack with few problems, according to Director of History for the U.S. Naval Institute, Paul Stillwell.  “Obviously, the weather did not deter the Japanese attack. They crossed the North Pacific in rough seas, and had to refuel their ships from oilers on the way over. But as far as weather for the attack, it was clear.”

Although weather conditions at the naval base were detrimental to the U.S., Stillwell further explains that meteorological conditions to the southwest of Pearl Harbor on December 7, 1941 actually worked to America’s advantage in some ways. “The USS Enterprise was coming back from Wake Island and was scheduled to arrive the morning of the 7th, but was delayed because of rough seas. The vessel was behind schedule returning to Pearl Harbor and because of this was not present for the attack.”

The spared aircraft carrier went on to play a very significant role throughout the remainder of the war, and had it been in port that day, the war may have had a very different outcome.

Clear visibility on December 7, 1941, resulted in a devastating blow to US Naval forces and a tremendous loss of life.  Twenty-one ships were lost or damaged, 347 aircraft were destroyed or damaged, and 2,403 Americans killed and another 1,178 injured.

On the 75th anniversary of Pearl Harbor, it’s interesting to research and analyze data from that historical day, but lest we forget, all of these facts and figures represent grieving families and lives cut short in the defense of our freedoms. In 2015, some 2,000 to 2,500 Pearl Harbor survivors were thought to still be alive but those numbers are shrinking with each passing year; so let me say, God bless every one of you and thank you for your service to our great country.