Monthly Precipitation
State of Hawaii Summary

The following excerpts are taken from the NOAA NWS Honolulu Forecast Office's Monthly Precipitation Summaries.

January: Most areas in the State of Hawaii experienced a very wet start to 2005 and a continued lack of sustained trade winds. The last time the main Hawaiian Islands experienced sustained trade winds lasting more than one day was back in early December 2004....A strong storm with a slow moving cold front that threatened the island chain at the end of December 2004 impacted Kauai on January 1 with 3 to 6 inches of rain, creating a very wet New Year's Day.... The storm pushed eastward, bringing 1 to 3 inches of rain and minor flooding on Oahu and Maui County by January 2. Areas along the south and west side of the Big Island also received 1 to 3 inches of rain on January 3 as the storm dissipated, with the Hamakua, Hilo, and Puna areas seeing less than 2 inches....On January 8, a strong and rapidly moving cold front brought heavy rains and severe thunderstorms to the western half of the state. A tornado touched down in Waimea, Kauai and damaging wind gusts of 50 to 70 miles per hour blasted several areas of Kauai and Oahu....See [the NWS-HFO] severe storm event summary for more details.... The period from January 12 through 25 saw relatively dry weather conditions, especially over the windward slopes of Maui and the Big Island....January closed out with the return of very unsettled weather. On January 29, a diffuse frontal boundary destabilized by a passing short wave trough brought heavy rainfall to south and east Oahu during the morning and early afternoon hours.

February: Unsettled weather over the Hawaiian Islands that started from the end of January continued through the first week of February. The unstable conditions were produced by a strong low pressure system that moved over the island chain from the west. Heavy rains affected all of the main islands in the state and flash flooding occurred on Kauai and the Big Island...The departure of the week-long storm marked the return of sustained trade winds to the Hawaiian Islands. A strong shear line reached Kauai and Oahu on February 11, bringing periods of heavy rains and strong northeast winds...The rest of February saw persistent trades in the moderate to fresh range punctuated by weak shear line passages on February 22-24 and on February 26. The shear lines brought enhanced trade wind showers but no associated flooding problems.

March: Non-trade wind conditions dominated the first 3 weeks of March with the main Hawaiian Islands in the low level westerly belt. On March 9 and 10, a cold front pushed across the island chain bringing with it an increase in rain shower activity. However, for Oahu and Molokai it was the pre-frontal convergence bands ahead of the cold front that dropped the most rain during the night of March 8 with several locations reporting over 2 inches within a 12-hour period....The last cold front of the month reached Kauai on March 25 and evolved into a shear line configuration. The shear line marked the return of persistent trades that continued through the end of the month as well as the start of very wet conditions for the windward areas of the state.

Kevin R. Kodama, Senior Service Hydrologist
National Weather Service Forecast Office, Honolulu, Hawaii