Oahu, Honolulu 10 Day Forecast
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Daily weather updates for all hawaiian islands, with weather forecast, conditions, climate for Honolulu, Kailua, Haleiwa, North Shore. Oahu weather today forecast with satellite pictures, news, tsunami warnings.
Oahu, like the other Hawaiian Islands’ tropical climate, is subject to variations of elevation and geographic location more than the seasons. Its rain-bearing trade winds are blocked by Oahu’s two parallel mountain ranges - Ko‘olau (reaching 3,105 feet), and Wai‘anae (reaching 4,020 feet).
Thus the southern and western (leeward) sides of Oahu - Honolulu, Waikiki, and Ko Olina - are drier and warmer than the windward side - Kailua and Aeia - and the North Shore near the surf town of Haleiwa. Winter season usually bring dangerous sea conditions to the north shore’s world-famous surfing beaches, perfect for big wave competitions, but perilous to novice surfers and swimmers.
Oahu has a spectacular, diverse climate and enjoys nearly perfect weather. Its daytime temperatures along the coasts generally range from only the mid-70s to the mid-80s most of the year. Oahu is the only state in the U.S. that has never recorded a sub-zero temperature.
Since Oahu has only two seasons—Summer (May through October) and Winter (November through April), you will experience more temperature variation between elevations and windward-leeward coasts, than you will between the seasons.
Oahu coastal temperatures can sometimes dip into the 60s during mid-winter and rise into to the 90s in mid-summer. Oahu's heaviest rains occur during winter-month storms, often riding Kona winds, which uncharacteristically blow from the southeast. Flash flooding is not uncommon at such times. Hurricane season in Oahu is June through November. Hurricanes are rare, occurring only about once every 10 years.
Oahu’s Beneficial Geography
Located between 19 and 23 degrees north latitude, the inhabited Hawaiian Islands lie only 1,200 to 1,600 miles north of the equator. This fortuitous circumstance of geography means the sun is high in the sky year round, creating temperatures that warm both the land and the surrounding ocean, which varies in temperature from only about 75 degrees to 83 degrees between winter and summer.
Such a warm surrounding ocean keeps the atmosphere above the Hawaiian Islands relatively warm. But two other factors contribute to Oahu’s reputation as a tropical paradise with diverse microclimates: Oahu’s trade winds, and Oahu’s numerous volcanic mountains.
Oahu Volcanic Mountains
The mountains of Oahu, formed millions of years ago though volcanic eruptions from the ocean floor - as the Pacific Plate moves slowly northwest over a hot spots in the earth’s mantle - affect Oahu's climate and account for the variations in weather from both island to island and on the same Island.
Oahu Trade Winds
In Oahu, the northeast trade winds, averaging 12 mph, occur about 90% of the time in the summer and about 50% of the time in the winter. They keep humidity at a minimum and ensure moderate temperatures, especially on the windward, unlike other tropical islands closer to the equator.
These cooling winds are created because warm air rises near the equator, flows northward through the upper atmosphere, and cools. Because it becomes heavier as it cools, it falls back to the earth’s surface at about 30 degrees latitude, where it flows back toward the equator to replace more rising warm air. This creates cool breezes moving from the northeast to the southwest along the ocean’s surface, and over the Hawaiian Islands.