Kailua-Kona, a town on the west side of Hawaiʻi Island was designated "Kailua-Kona" by the U.S. Postal Service to differentiate the Big Island village of Kailua from an Oahu town by the same name, located on the windward side of Oahu island. In Ōlelo Hawai'i (the Hawaiian language), Kailua means "two seas" or "two currents," a contraction of the words "kai" (meaning "sea" or "sea water") and "’elua," (meaning "two").
Meanwhile, the term "kona" means "leeward side" in Ōlelo Hawai'i, so all Hawaiian islands have a kona side. Hawai'i's prevailing winds predominate from the east/northeast, so the kona side is the west side of each island. That's why it's somewhat erroneous to call any town "Kona," since you're actually calling it "leeward." Still, most Big Island residents say things like, "I had to drive to Kona today," or "I'm heading to Kona. Do you need anything?" I doubt that will ever change.
Just to keep things honest, Hawai'i's highway signs correctly direct you either to "Kailua" or "Kailua-Kona." So after you rent that expensive convertible at the airport, aim for the arrow on that green sign pointing to Kailua, and you'll arrive at the town you always thought was Kona, which is "kona" (lower case) most of the time.
The "Kona Side" is Not always Leeward
Trade winds account for 70 percent of all breezes in Hawaii and are the most common winds over local waters. These winds blow from the northeast or east-northeast and became known as "trade winds" hundreds of years ago when cargo ships depended on the strong winds for speedy passage.
During Hawaiian summers, the trades prevail about 90 percent of the time, sometimes persisting an entire month. However, from January through March, the trade winds may occur only 40 to 60 percent of the time. Though brisk and refreshingly cool over land, gusty trade winds wreak havoc for mariners when brutal winds swirl through the channels between islands. Trade winds are usually at their lowest frequency in September and October, however, that's when temperatures rise for island residents, and they yearn for the return of their beloved trades.
"Kona Winds" is a local term for the breezes that blow from the southwest or south-southwest—the opposite of the trade winds. In such a case, the western side of the Big Island then becomes the windward side, since the predominant wind pattern is reversed. The warmer and more humid Kona Winds usually don’t last long, when the prevailing "trades" resume their cooling breezes, and locals breath a sigh of relief.
As you can tell, Ōlelo Hawai'i and local-lingo can be turned upside down by a number of things, including the winds, haoles (foreigners), the multiple meanings of Hawaiian words, and the U.S. Postal Service. Perhaps we should tell you the story of Waimea, a town on the Big Island that shares its name with Kauai's Waimea and Oahu's Waimea. All three Waimeas stem from the Ōlelo Hawai'i word for "reddish water." To avoid confusion, the U.S. Postal Service decreed that the Big Island's Waimea should be called "Kamuela," much to the dismay of local residents. By the way, Kamuela is the Ōlelo Hawai'i term for "Samuel," and there is even more confusion about where that came from.
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