State of Hawaii
Seasonal Precipitation Summary

The 2009-2010 Hawaiian Islands wet season ranks as the driest in the past thirty years. The recently completed October 2009 - April 2010 Hawaiian Island wet season, or "Hooilo", ranks as the driest in the past thirty years and on of the driest in the past 55 years. This is based on an average of wet season rainfall rankings from seven reporting stations across the state with continuous records. These stations are Lihue Airport, Honolulu Airport, Manoa Lyon Arboretum, Molokai Airport, Ulupalakua Ranch, Kapapala Ranch, and Hilo airport. Note that overall ranking can vary depending on the stations used in the calculation.

As highlighted in an October 20, 2009 NOAA media release, the development of an El Niño during the summer of 2009 resulted in a forecast of drier than normal conditions in the Hawaiian Islands following the hurricane season. Existing agricultural drought in the eastern half of the state worsened, especially in the Kona, Kua, and Leeward Kohala sections of the Big Island. Impacts to Agricultural Operations span a wide range of sectors including livestock, coffee, and ornamental flowers. Residents depending on rainfall catchment also suffered from the dry conditions and required costly water delivery to meet basic needs. Please refer to the latest drought information statement at:
http://www.prh.noaa.gov/hnl/pages/watchwarn.php.

For comparison purposes the following are the 5 wettest and 5 driest October - April wet seasons over the last thirty years:

5 Wettest:
1. 1981-1982
2. 1988-1989
3. 1996-1997
4. 1990-1991
5. 2003-2004

5 Driest:
1. 2009-2010
2. 1997-1998
3. 1991-1992
4. 1980-1981
5. 1999-2000.

Additional individual rainfall station information and specific island information for Hawaii can be found in the Monthly Precipitation Summaries.

Hawaii Rainfall Summary for Select Stations, 2nd Quarter and 1st Half 2010

Climate Outlook: The following comments are from the U.S. Climate Prediction Center's Seasonal Outlook Discussion:

"Moderate to exceptional drought (D1 to D4 designations) continues across the leeward sides of the Hawaiian Islands. Forecasts for these areas call for below median rainfall during August - October, leading to drought persistence. A relatively dry climatology also supports persistence. Beyond this time period, expected wetness associated with La Niña conditions may bring improvement during the 2010-11 winter season."

For more information on weather and climate in Hawai'i go to:
http://www.prh.noaa.gov/pr/hnl/ or http://www.cpc.noaa.gov/products/predictions/long_range/fxhw40.html