In 1941, Hawaii was a territory of the US with statehood some eighteen years away. As early as the 1870’s, the US military had scoped out the islands for commercial and defensive potential and decided that Pearly harbor on the south side of Oahu about ten miles northwest of Honolulu fit the bill. With the persistent trade winds blowing from the northeast most of the year, this particular part of Oahu is in the rain shadow of the Koolau Range. While clouds and rain are common in the Koolau Range, the downsloping winds tend to dry out for southern side of the island. In fact, Honolulu averages only about 17 inches of rainfall in a given year due to the drying effects of the downsloping winds.
On the morning of December 7th, 1941, the weather observer at Hickam Field in Honolulu reported mainly clear skies each hour with mild temperatures and light east-to-northeast winds. There was nothing that would obstruct fighter pilots lines of sight, no heavy cloud cover and no heavy rains to make flight difficult on that fateful day. After crossing the rough waters of the North Pacific, the Japanese fighter pilots in more than 350 planes reported seeing a “long white line of coast” referring to Oahu’s Kakuku Point (according to National Geographic, AccuWeather). In summary, as far as the weather was concerned, all was favorable for the attack that had been planned “many days or even weeks in advance” according to President Roosevelt in his famous speech given on the following day.