Monthly Climate and Impacts Report for Hawaii - October 2012

Chris O'Connor and Dr. Pao-Shin Chu
Hawaii State Climate Office
Department of
University of Hawaii
Honolulu, HI 96822

Precipitation and Temperature

October 2012 was significantly drier than normal, as we saw the currently ongoing dry trend not only continue but worsen. This dry trend was present throughout the entire summer and is now showing strong into autumn. On Oahu and Maui we experienced as close to absolute dry conditions as we could have experienced throughout the entire month, as the greatest amount of rainfall felt was traces at best. Lihue on Kauai was the only major airport location in the state that saw slightly greater than normal rainfall, which was an interesting characteristic. Hilo saw a consistent trend of rainfall all month, however experienced overall much lower than normal precipitation. Drought conditions across the state remained approximately the same from last month, with Oahu and Kauai ranging from "Abnormally Dry" (D0) to "Severe Drought" (D2), while the eastern islands have areas ranging from "Abnormally Dry" (D0) to "Extreme Drought" (D3) on a scale of D0-D4. Interestingly, Niihau is completely drought free, as well as northeastern shores of Oahu, Maui and Hawai'i.

Across the state, mean temperatures as well as mean highs and mean lows were below their respective historical averages.   Generally this is a sign of increased cloudiness blocking both incoming solar radiation and outgoing longwave radiation, effectively reducing the diurnal temperature range. This is confirmed by observations, three of the four airports had more than 23 days as "partly cloudy" or cloudier. Kahalui airport was the exception, as it had only 6 partly cloudy days, and 25 clear days.

The NOAA Climate Prediction Center seasonal outlook for Hawaii predicted below normal precipitation and below normal temperatures for the entire state in November 2012.


After experiencing La Nina conditions the past two winters, we are now identifying a shift in the behavior of the ENSO cycle. Positive Sea-Surface-Temperatures have been recorded since April 2012, triggering a shift from La Nina conditions to ENSO-neutral conditions, which have continued into October. Equatorial sea surface temperatures remain above average across the western and central Pacific Ocean, while the atmospheric circulation over the tropical Pacific is near average. The general consensus is that we are in fact seeing a borderline ENSO-neutral/ weak El Nino formation for next winter, possibly strengthening during the next few months.


The 2012-2013 "wet season" began this past month with more than half of the state in drought. We ended October no better than coming into the month, as we saw very minimal precipitation throughout the state. The Hawaiian weather was very dry throughout the month and the effects of drought are continuing to be felt state-wide. As a result, voluntary restrictions on water use remains in place as a precaution for the dry season.  On Kauai, the area of drought impacts are continuing to spread westward.  Oahu is experiencing similar impacts to recent months: poor condition of pastures and visible dryness of the landscape. Hawai'i desperately needs significant precipitation.

On a different note, Hawai'i and the entire Pacific Ocean received another tsunami warning this month on 10/27/2012.  Although the maximum size wave that experienced was about 2ft in height, tsunami warning evacuations were put in place to ensure proper preparation.  Many beachfront businesses closed, causing loss in business for the night and resulted in many unsatisfied yet compliant customers. Also, beachside residents were strongly urged to evacuate, only to later learn that there was no need. Remember, it's always better to be safe than sorry!