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Decline in rainfall for Hawaiʻi

By: Chaz Mihara

7 November 2019

Hawaiʻi has seen less rainfall in 2019. But when it does rain, it's much more massive. Rain comes in stretches.


According to the City and County of Honolulu Climate Change Commission, declining rainfall has occurred in both wet and dry seasons and has affected all the major islands. Significant rainfall events and droughts have become more common, increasing runoff, erosion, flooding, and water shortages.

For March, conditions were stable and dry. It was the driest March for several locations in over a decade, according to the National Weather Science.


The Big Island experienced minor flooding with one to four inches of rainfall in the area of Honaunau and Kealakekua.


Interestingly, we see a bit of heavy rainfall towards the ending of months. During the last week of June, Kauaʻi, Oʻahu, Molokaʻi, and Lanai experienced heavy rainfall of three to five inches, according to the NWS.

In August, there were two tropical cyclones. The first cyclone Erick, passed through the south of the Hawaiian Islands. Kauaʻi experienced most of the effects with heavy rainfall and thunderstorms. Three to four inches of rain called for a flash flood warning that blocked access to homes in Kappa, according to the NWS. The second tropical cyclone Flossie, was not as intense as cyclone Erick, and there were no impacts of flooding throughout the islands.


November was split in half as the first part of the month was dry, and the second half was wet. According to the NWS, on Nov. 16, an intricate pattern involving a cold front approaching Kauaʻi, a surface trough near the Big Island, and a low-pressure system aloft combined to produce heavy rainfall and thunderstorms across the state. On Nov. 17, Kauaʻi had heavy rainfall that overflowed Hanalei River and closed Kuhio Highway. Thunderstorms started to develop over Oʻahu, Maui, and the Big Island.


Recently, Hawaiʻi experienced thunderstorms. Heavy rain pour filled the Hawaiian Islands. Many areas lost power and trees fell, covering sidewalks and roads.  


Now, we are transitioning to the wet season of the year. 


As the end of the year is approaching, the hope is for safe weather across the Islands.

In January, conditions were dry. These impacts are mainly affect ranching operations and help increase the risk of brush fires outside the typical fire season, according to the National Weather Service.  


In the middle of February, the Hawaiian Islands experienced periods of heavy rainfall. For the island of Oʻahu, peak rainfall totals of four to six inches occurred over the northern half of the Koʻolau Range. In late February, there was a weak, cold front across the state that lead to stable conditions.


Photo by: Chaz Mihara

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