Big Island ends extremely dry 2025 with a mostly dry December

The Big Island missed out on rainfall from a few passing fronts in December, keeping the majority of the island pretty dry and below average — many places at less than 50% of their normal rainfall — for the last month of 2025.

Overall, the Big Island had an extremely dry year.

Hilo Airport had its second-driest December in the past 35 years, collecting just 3.84 inches of rainfall compared with its normal 12.07 inches, or just 32% of average.

Kawai Nui Stream recorded its driest December on record — since 2010 — with 4.13 inches collected throughout the month, or 31% of its average total of 13.42 inches of rainfall for the last month of the year.

Other significantly dry rain gauge sites around the island last month included:

• Mauna Loa Observation Station: 0 inches (0% of average 1.32 inches).
• Puhe CS: 0.02 inches (1% of average 1.76 inches).
• Pōhakuloa Training Area Range 17: 0.04 inches (2% of average 1.73 inches).
• Pōhakuloa Training Area Kīpuka ʻAlalā: 0.08 inches (6% of average 1.38 inches).
• Kahua Ranch: 0.47 inches (8% of average 6.25 inches).
• Pu‘u Mali: 0.22 inches (8% of average 2.9 inches).
• Waimea Plain: 0.34 inches (9% of 3.69 inches).
• Honoka‘a: 0.8 inches (9% of average 9.3 inches).
• Kamuela 1: 0.56 inches (11% of average 4.88 inches).
• Nēnē Cabin: 0.74 inches (13% of average 5.58 inches).
• Pōhakuloa Training Area West: 0.29 inches (16% of average 1.85 inches).
• Pu‘u Wa‘awa‘a: 0.33 inches (17% of average 1.99 inches).
• Kaʻūpūlehu: 0.31 inches (18% of average 1.72 inches).

All other gauges around the island reporting to the National Weather Service saw at least 20% of their monthly December rainfall average.

Portions of the Kona districts on the west side of the island actually did see some unseasonably high rainfall last month, with 2 to 3 inches throughout the course of December, because of deep tropical moisture and southerly winds ahead of a couple of those fronts.

Several sites between Hōnaunau and Ellison Onizuka Kona International Airport ended December with above average rainfall totals.

Sites that were at average or above last month included:

• Hōnaunau: 2.81 inches (100% of average 2.8 inches).
• Kāʻināliu: 3.3 inches (121% of average 2.73 inches).
• Puho CS: 2.29 inches (124% of average 1.84 inches).
• Kealakekua: 3.64 inches (133% of average 2.74 inches).
• Wai‘aha: 3.59 inches (135% of average 2.66 inches).
• Waiki‘i: 25.85 inches (105% of average 24.67 inches).
• Waikōloa: 13.07 inches (103% of average 12.72 inches).

Only 13 other rain gauges around the island saw at least 50% of their average December rainfall, but still did not reach their norms.

The highest monthly total rainfall on the Big Island for December came at the Honoli‘i Stream gauge near Hilo, with 7.88 inches. That was still, however, just 46% of its monthly average.

Highest daily rainfall total was collected by the Saddle Road Quarry gauge with 5.16 inches, which was still just 44% of its average December total of 12.82 inches.

Seven sites in the Hāmākua and Hilo districts reported their driest calendar years in their respective periods of record, most notably the Hilo Airport with its driest year since 1949.

The airport rain gauge collected just 58.95 inches or rainfall throughout the entire year, only 49% of its annual average of 120.39 inches.

The other 6 driest sites were:

• Kamuela (since 1997): 17.01 inches (29% of average 57.96 inches).
• Laupāhoehoe: 54.05 inches (35% of average 156.12 inches)
• Mountain View: 89.42 inches (52% of average 172.4 inches)
• Waiākea Uka (since 1991): 82.35 inches (42% of average 196.2 inches)
• University of Hawaiʻi Waiākea Experimental Station (since 2010): 75.41 inches (47% of average 161.73 inches)
• Waimea Plain Natural Resources Conservation Service Soil Climate Analysis Network (NRCS SCAN) site (since 2012): 11.96 inches (27% of average 44.54 inches).

Hakalau Remote Automatic Weather Stations (RAWS) also had its second-driest calendar year since 2004. It recorded 49% of its annual average: 37.78 inches compared with 77.75 for its norm.

Elsewhere, year-to-date values were generally 30% to 70% of average for the year. However, the beneficial rainfall during the summer helped keep portions of the Kona and Kohala districts above average for the year.

Sites that saw above average rainfall throughout 2025 included:

• Wai‘aha: 85.11 inches (180% of average 47.3 inches).
• Ellison Onizuka Kona International Airport: 12.75 inches (129% of average 9.87 inches).
• Kealakekua: 65.08 inches (116% of average 56.24 inches).
• Kaloko-Honokōhau: 22.38 inches (114% of average 19.56 inches).
• Kāʻināliu: 59.19 inches (109% of average 54.51 inches).
• ‘Ahumoa: 22.46 inches (106% of average 21.22 inches).
• Waiki‘i: 25.85 inches (105% of average 24.67 inches).
• Waikōloa: 13.07 inches (103% of average 12.72 inches).
• Pu‘u Wa‘awa‘a: 24.6 inches (101% of average 24.36 inches).

The Kawai Nui Stream rain gauge recorded the highest year-to-date total with 112.32 inches, which was still 83% of its average 135.26 inches.

December began with dry and stable conditions throughout the state, as light southeasterly winds and localized land and sea breezes prevailed ahead of an approaching front.

A weak front stalled Dec. 3 near Kauaʻi, bringing showers embedded in southerly flow to Kauaʻi and Niʻihau into Dec. 4.

High pressure rebuilt northeast of the state as the front retreated back to the west, allowing east to east-southeasterly trade winds to strengthen, with typical scattered windward and mauka showers.

Winds weakened and veered southeasterly to southerly again by about Dec. 8-9 as another front approached. That front brought a wetter pattern statewide through Dec. 11, followed by cooler northerly winds in its wake.

A stronger mid-month front that proved to be the most significant weather-maker of December then moved over the islands, with trade winds returning from Dec. 21-23, bringing more stable conditions.

Moisture from a remnant front was pushed south during that period, enhancing showers along windward slopes and producing rainfall of about 1 to 2 inches on most islands.

Drier and locally breezy trades prevailed through Christmas Eve and Christmas Day, followed by weakening winds and a shift back toward an east-southeasterly direction ahead of another front.

The month ended with moderate trades and generally dry conditions, despite a brief surge of moisture the morning of Dec. 30 that slightly enhanced windward showers.

No significant impacts were reported.

The monthly rainfall summary was prepared by National Weather Service Forecast Office Honolulu Senior Service Hydrologist Tina Stall.

News reporter Nathan Christophel contributed to this story.