Parched: Some Parts of Big Island Broke Records For Lowest August Rainfall Totals

To say August was a dry month on the Big Island might be a slight understatement.

Rainfall totals for last month recorded by rain gauges on the island were mostly below average, with many at less than 50% of average, according to the monthly precipitation summary prepared by Kevin Kodama, senior service hydrologist with the National Weather Service in Honolulu.

“Records for the lowest August total were broken at Glenwood, Honokaʻa, Laupāhoehoe, Mountain View, Piʻihonua and Waiākea Uka,” Kodama’s report said. “The Kamuela and Kamuela Upper gauges had their lowest August totals since 2008 and 2011, respectively.”

The U.S. Geological Survey’s rain gauge at Honoliʻi Stream recorded the highest monthly rainfall total for the island with 7.42 inches. That’s still 38% of average. The same gauge also had the highest daily total of 1.92 inches of rain on Aug. 5.

Kodama reported that rainfall totals for 2022 through the end of August were near to below average at most of the island’s gauges as well. The USGS gauge at Kawainui Stream had the highest year-to-date total by the end of the month with 126.13 inches of rain, which is 126% of its average.

For a map of year-to-date rainfall totals on the island, click here.

Trade winds were present throughout the main Hawaiian Islands during most of August, but were weaker and less consistent than in June and July, Kodama’s report said. There were three breaks in the trades, all of which produced short periods of heavy rainfall for some parts of the state.

The first break was Aug. 3-5, which saw a weak low pressure trough pass westward just north of the state. That allowed land and sea breezes to dominate conditions. Parts of Maui and Oʻahu saw brief but heavy afternoon showers, with some spots on Oʻahu seeing some minor flooding but no significant damage.

The second break in trades from Aug. 15-17 was caused by another weak low-level trough. The windward slopes of the Koʻolau Range on Oʻahu, from Kāneʻohe to Kahuku, seeing the most significant rainfall during the break.

During the third break, from Aug. 22-25, the Big Island got in on some of the precipitation. Peak 24-hour rainfall totals were in the range of 1-2 inches over the windward side of the Kohala Mountains and portions of windward and west Kauaʻi and along the windward slopes of Oʻahu, Molokaʻi and Maui.

August also is normally the peak month for tropical cyclone activity in the central North Pacific basin, but there were no tropical cyclones the entire month. A weak tropical disturbance passed to the south of the state Aug. 10-11, but only caused an increase in trade winds and no significant spike in rainfall.

Kodama reported that while some parts of the islands received much needed rainfall during August, areas hardest hit by drought, including central Maui and west Molokaʻi, did not have enough rain to improve conditions. For additional drought details, refer to the Drought Information Statement online.