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

The spring season has brought improving trends in rainfall amounts to most of the islands of Hawai'i. May produced an average amount of moisture for the state, besides the far western islands (Kauai). Kauai saw much drier than normal conditions while the islands to the east experienced normal precipitation conditions. Kahului experienced average rainfall amounts (~106.78% of normal) for the first time this spring after seeing a wet winter season. Hilo experienced slightly less rainfall than Kahului however still close to the normal amount of rainfall (81.29% of normal), which is a sharp contrast to the minimal amount of precipitation Hilo experienced in the first two months of spring (~25-30% of normal). Oahu experienced above average precipitation for the third month in a row (111.29% of normal). Kauai, the western most island of the state, was much less fortunate than her sister islands, pulling in well below average rainfall amounts. Lihue saw 28.02% normal rainfall. This is in contrast to above average rainfall in Kauai the first two months of spring. As a result of the overall increase in precipitation this spring, drought conditions in the western part of the state have seen a continued improvement from previous months. Both Oahu and Kauai have improved to drought free conditions! The eastern islands have seen a slight decrease in drought this spring. There are still areas of drought in this part of the state ranging from "Abnormally Dry" (D0) to "Extreme Drought" (D3) on a scale of D0-D4. The big picture: thanks to a couple of healthy months of rainfall during winter and spring seasons, drought conditions have improved greatly in the western part of the state and continued to improve in the eastern part of the state!

Temperature anomalies were very interesting this month. Just as the state experienced di-polar precipitation regimes, temperature regimes can be split into two sections: eastern and western islands. In the eastern Hawaiian islands, the mean temperatures as well as mean highs and mean lows were above their respective historical averages. In the western Hawaiian islands, the mean temperatures as well as mean highs and mean lows were below their respective historical averages.

The NOAA Climate Prediction Center seasonal outlook for Hawaii predicted equal chances for above, near, and below normal temperatures for the Hawaiian Islands in May 2013. They also give no indication of either above or below median precipitation for Hawaii in May 2013.

During May 2013 ENSO-neutral continued. Equatorial sea surface temperatures (SST) are near average across the western and central Pacific Ocean and below average across the eastern Pacific. ENSO-neutral is favored into the late Northern Hemisphere summer 2013.

May 2013 saw some very interesting activity in terms of weather in the state of Hawai'i, as several records were set concerning precipitation and temperature. On Wednesday 5/1/13 a high temperature of 89 degrees at Kahului broke the old record of 88 degrees set in 2011. Then on Saturday 5/4/13 and Sunday 5/5/13, a record high temperature of 89 degrees was tied at Kahului. Monday 5/20/13 brought a record low temperature of 60 degrees to Lihue, breaking the previous record of 61 degrees set in 2009. Then again in Lihue a record high temperature of 86 degrees was experienced on Thursday 5/29/13, breaking the previous record of 85 degrees set in 1996.

There were three rainfall events which set a record this month, occurring at the Kahului airport. On Saturday 5/11/13, a record rainfall of 0.17 inches was observed in Kahului, breaking the old record of 0.11 inches set in 1968. Then on the following day 5/12/13 a record rainfall of 0.21 inches was observed in Kahului, breaking the old record of 0.03 inches set in 2000.