Weather & Climate
Rainfall Atlas of Hawaii
The 2011 Rainfall Atlas of Hawai‘i was developed by the University of Hawai‘i at Manoa (UHM), Department of Geography, as part of an agreement between the Commission on Water Resource Management and the U.S. Army Corps of Engineers, Honolulu District. This project is a major update of the original Rainfall Atlas first published in 1986. The Rainfall Atlas of Hawai‘i is comprised of maps of the spatial patterns of rainfall for the major Hawaiian Islands and represents the best estimates of the mean rainfall for the 30-year base period 1978-2007. The UHM Geography Department has developed an easy-to-use and informative website hosting the Rainfall Atlas report, an interactive map, GIS layers, tabular data, and more.
Rainfall Atlas of Hawai‘i Website 
The video below is a presentation by Dr. Thomas Giambelluca, Professor of Geography at the University of Hawaii Manoa, discussing the methodology and findings of the investigation that went into developing the 2011 Rainfall Atlas of Hawaii.
The original 1986 Rainfall Atlas of Hawaii was also developed by Dr. Thomas Giambelluca, et al. with support from the Department of Land and Natural Resources, Division of Water and Land Development. The 1986 Atlas has served as the rainfall standard for the past 25 years.
Report R76, Rainfall Atlas of Hawaii, June 1986 [17.7 MB]
TopEvapotranspiration in Hawaii
The Commission is partnering with the U.S. Army Corps of Engineers and the University of Hawaii to develop evapotranspiration estimates for the State of Hawaii. Evapotranspiration is the combined loss of water from the land surface through the process of evaporation and plant transpiration. Evapotranspiration and rainfall are key factors used to estimate the availability of ground and surface water in Hawaii. In this project, remote sensing data from satellites will be used to estimate net radiation, air temperature, relative humidity and wind speed. These elements will be combined to produce unprecedented digital maps of estimated mean monthly and annual evapotranspiration. This project is scheduled to be completed by early 2013.
The video below is a presentation by Dr. Thomas Giambelluca, Professor of Geography at the University of Hawaii Manoa, discussing the status of a current project to establish evapotranspiration rates in the State of Hawaii. Dr. Giambelluca is the principal investigator on this joint effort between the Commission and the U.S. Army Corps of Engineers.
Other Evapotranspiration Resources
USGS Scientific Investigations Report 2008-5163, The Significance of Accounting Order for Evapotranspiration and Recharge in Monthly and Daily Threshold-Type Water Budgets, Delwyn S. Oki.
Report R74, Pan Evaporation: State of Hawaii, 1894-1983 [10.3 MB]
Weather Resources on the Web
Many gonvernment agencies and educational institutions, often in collaboration, collect, analyze, and disseminate weather and climate information. Listed below are a few internet resources that will aid in learning more about Hawaii's climate.
National Weather Service Honolulu
National Weather Service Honolulu Climate Page
Western Regional Climate Center
National Integrated Drought Information System
