July was dry on the Big Island

If you haven’t noticed, it’s been pretty dry on the Big Island lately.

Big Island rainfall totals for July were mostly below average, with many totals ranging from 30% to 70% of average. The Pāhoa rain gauge had its lowest July total since 2004, and area didn’t even record getting any rain last month.

According to the monthly rainfall summary from the National Weather Service in Honolulu, the Pāhoa rain gauge normally gets an average of 11.38 inches of rain in July. This year, it recorded a measely 4.73 inches.

Puhe on the northwest coast of the island, which granted only records on average 0.36 of an inch of rain in July, didn’t get one drop of rain last month.

Kohala Ranch, also on the north side of the island, also normally gets an average of less than half an inch of rain in July but this year got what you could consider just a trace with just 0.02 of an inch, or 4% of its monthly average.

Then there was the Kaupulehu gauge, on the west side of the island, that usually sees an average of 1.19 inches of rain for July but this year only recorded 0.04 of an inch last month, which is just 3% of its July average.

Even Hilo, with its claim as the rainiest place in the United States, was drier than usual in July. The Hilo International Airport rain gauge, normally on average recording 9.24 inches of rain in July, saw 4.84 inches last month, or just 52% of its average.

There were some wetter spots on the island, but not many.

Portions of the Hāmākua Coast northwest of Paʻauilo and the windward slopes of the Kohala Mountains were the main exceptions to the dry norm last month, with near to above average rainfall in those areas.

The U.S. Geological Survey rain gauge at Kawainui Stream had the highest monthly total of 16.20 inches, or 120% of its July average, and the gauge at Honoliʻi Stream north of Hilo had the highest daily total for July of 4.14 inches on July 19.

However, for the month, the Honoliʻi Stream gauge recorded 12.61 inches, which is 57% of its 22.09-inch July average.

Trade winds persisted throughout all of July and continued a generally dry and stable trend that started in June.

On July 19, a weak surface trough east of the main Hawaiian Islands provided the Big Island’s rainiest day of the month. Rain gauge data and bias-adjusted radar rainfall estimates showed 2 to 5 inches over the windward slopes from Hāmākua to Puna.

Enhanced moisture from the remnant of a weak tropical disturbance provided a boost in rainfall July 23 over windward slopes of the state.

The Big Island, Oʻahu and Kauaʻi saw daily totals of 1 to 2 inches.

Windward Maui’s totals were a bit higher, with isolated amounts reaching 2 to 4 inches.

The below average rainfall and higher seasonal temperatures have increased drought coverage and intensity throughout the past month, especially in the leeward areas.

As of Aug. 6, according to the U.S. Drought Monitor, nearly 95% of the Big Island was either abnormally dry or under moderate to severe drought; 13% of the island was experiencing severe drought alone.

An estimated 74,336 people were living in drought areas.

However, rainfall totals for the year through the end of July were near to above average at most of the rain gauges on the Big Island.

The U.S. Geological Survey rain gauge at Honoliʻi Stream had the highest year-to-date total of 129.37 inches, or 97% of average.