Kona low

Kona storms (also called Kona lows) are a type of seasonal cyclone in the Hawaiian Islands, usually formed in the winter from winds coming from the westerly "kona" (normally leeward) direction. They are mainly cold core cyclones, which places them in the extratropical cyclone rather than the subtropical cyclone category. Hawaii typically experiences two to three annually, which can affect the state for a week or more. Among their hazards are heavy rain, hailstorms, flash floods and their associated landslides, high elevation snow, high winds which result in large surf and swells, and waterspouts.

Kona is a Hawaiian language term (related to similar words in other Polynesian languages) for the western (to southwestern) side of an island. The Kona District for example on the Big Island of Hawaiʻi still uses this name. Although normally dry and leeward, the traditional easterly (to northeasterly) tradewinds slacken and reverse during one of these cyclones.

Once termed as subtropical cyclones, a change in the definition of the term during the early 1970s makes categorization of the systems not straightforward. Kona lows are typically cold core, making them extratropical cyclones. However, they generally share the subtropical cyclone characteristic of losing their associated weather fronts with time, since the cyclones tend to retrograde slowly.

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