According to global insurance and reinsurance broking group Aon’s weekly catastrophe report, back-to-back Kona Storms on March 10-24, which produced extreme rainfall and subsequent flooding across much of Hawaii, will result in total economic and insured losses of at least one billion US dollars, citing Hawaii government officials.
Aon’s report explains that the loss figure also includes notable agricultural impacts, as recent surveys found farmland damage worth more than USD 9.4 million, with over USD 2.7 million in farmland damage occurred in O‘ahu alone.
The broker emphasises that losses will continue to develop in the next few weeks and months as more damage assessments are conducted, suggesting insured and economic losses could increase.
O‘ahu was severely affected, particularly the northern parts of the island, namely, the North Shore communities of Waialua and Haleiwa, where devastating flash floods and landslides damaged hundreds of homes, farmlands, and roads statewide.
To recap, two Kona Storms on March 10-16 and March 19-24 brought torrential rainfall across the entire state of Hawaii. “Kona Storms” refers to slow-moving low-pressure systems that typically form between late fall and early spring months.
The heavy rains from the first Kona Storm resulted in an increased risk of flash flooding for the second Kona Storm on March 19- 24.
Aon states that the most extreme rainfall occurred overnight on March 19-20, particularly in the northern portion of O‘ahu, where some locations recorded nearly a foot of rain, causing severe flash flooding and landslides.
Overall, the two-week-long period was the heaviest rainfall event for Hawaii since 2004, with total rainfall maximums reported at the Kaala (O‘ahu) and Puu Kukui (Maui) mountain summits, which exceeded 52 inches (1.3 meters).
The events damaged nearby schools, hospitals, and airports, and 230 people were rescued from floodwaters while at least 5,500 people were issued evacuation orders. Officials also warned of failure at the Wahiawa Dam, though water levels have stabilised in recent days.
