Hilo

Tonight: Showers early in the evening, then showers likely in the late evening and overnight. Lows 60 to 69 near the shore to 52 to 58 at 4000 feet. Light winds. Chance of rain near 100 percent.

Thursday: Mostly cloudy. Showers likely early in the morning. Scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 80 near the shore to 64 to 69 at 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Scattered showers early in the evening. Locally heavy rainfall possible early in the evening. Lows 61 to 70 near the shore to 53 to 60 at 4000 feet. South winds up to 15 mph. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Lows around 71 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 40 percent.

Thursday: Mostly cloudy. Isolated showers early in the morning. Scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 80 to 85 near the shore to around 66 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Scattered showers early in the evening. Locally heavy rainfall possible early in the evening. Lows around 72 near the shore to around 52 near 5000 feet. South winds around 10 mph. Chance of rain 50 percent.

Waimea

Tonight: Mostly cloudy with isolated showers. Lows 61 to 70 near the shore to 55 to 62 near 3000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly cloudy. Showers likely in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 78 near the shore to 68 to 74 near 3000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Showers likely early in the evening. Locally heavy rainfall possible early in the evening. Lows 62 to 70 near the shore to 55 to 62 near 3000 feet. Light winds. Chance of rain 70 percent.

Kohala

Tonight: Mostly cloudy with isolated showers. Lows 61 to 70 near the shore to 55 to 62 near 3000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly cloudy. Showers likely in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 78 near the shore to 68 to 74 near 3000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Showers likely early in the evening. Locally heavy rainfall possible early in the evening. Lows 62 to 70 near the shore to 55 to 62 near 3000 feet. Light winds. Chance of rain 70 percent.

South Big Island

Tonight: Showers early in the evening. Lows around 74 near the shore to around 55 near 5000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain near 100 percent.

Thursday: Mostly cloudy. Isolated showers in the morning, then showers in the afternoon. Locally heavy rainfall possible late in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. South winds up to 10 mph. Chance of rain 80 percent.

Thursday Night: Mostly cloudy. Showers early in the evening. Locally heavy rainfall possible early in the evening. Lows around 73 near the shore to around 56 near 5000 feet. Light winds. Chance of rain 80 percent.

Puna

Tonight: Showers early in the evening, then showers likely in the late evening and overnight. Lows 60 to 69 near the shore to 52 to 58 at 4000 feet. Light winds. Chance of rain near 100 percent.

Thursday: Mostly cloudy. Showers likely early in the morning. Scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 80 near the shore to 64 to 69 at 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Scattered showers early in the evening. Locally heavy rainfall possible early in the evening. Lows 61 to 70 near the shore to 53 to 60 at 4000 feet. South winds up to 15 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly cloudy. Scattered showers early in the evening. Lows around 72 near the shore to 51 to 56 above 4000 feet. Light winds. Chance of rain 50 percent.

Thursday: Mostly cloudy. Scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 83 near the shore to 64 to 70 above 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Scattered showers early in the evening. Locally heavy rainfall possible early in the evening. Lows around 73 near the shore to 52 to 57 above 4000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A weather pattern featuring light winds, mostly cloudy skies, and scattered to numerous showers will continue through tonight. The weather will once again become more active beginning as early as Thursday as a new low develops, bringing renewed chances for heavy rain and moderate kona winds, especially for Friday into the weekend. Given the high soil saturation from the recent kona storm, even moderate rainfall rates could pose a risk for rapid runoff and flooding, especially during the latter portion of the week. The extended range forecast shows cool northeasterly trade winds returning from Monday into Tuesday, wet trade winds are expected to last through much of next week.

Short term update

Deep cloud cover continues to develop over the Hawaii region in response to a low pressure system moving in from the west with upper level troughing and jet stream support. Expect a brief break in the widespread rainfall in a southeasterly wind flow pattern lasting into Thursday morning. Winds then veer from a more southerly direction from Thursday afternoon onward, pulling up additional moisture from the deep tropics. Several weak surface lows, supported by upper level troughing, will drift through the islands from Thursday night through Sunday. The large scale forcing will move the heaviest showers to different islands in pulses of activity throughout this event.
A Flood Watch remains in effect for most of the Hawaiian Islands for this event. This watch may be expanded statewide as run to run model guidance continues to show differences in where and when the heaviest showers may develop.

Prev discussion

Issued at 316 PM HST Wed Mar 18 2026
Elongated surface troughing extending from a low in the NW Pacific serves as the focus for weak surface low development around 170W west of Kauai this afternoon. This low is forming within a corridor of very subtle height falls and is characterized by a very light wind field. In advance of the low, deep layer subsidence prevails over the islands in maintenance of benign weather tonight into Thursday. Mid-level forcing steadily increases Thursday into Saturday allowing aforementioned low pressure strengthen and increasingly deep SW flow to deliver waves of moderate to heavy rainfall to the islands heading into the weekend.
Thursday night. Visible satellite indicates ample upstream moisture in the form of a high coverage of low clouds and a few thunderstorms well west of Kauai. This will be the initial moisture push into the forecast area late Thursday as forcing steadily increases and advances eastward. Soundings remain fairly saturated from moisture left in place by the last event and PWATs on this morning's Hilo sounding were in excess of 2″. The initial slug of moisture also arrives coincident with a moderate increase in conditional instability in the column. These factors increase confidence in model depictions of deep convection with relatively high rain rates. Low-level convergence is sorely lacking during this time, but strengthening SW aloft will provide a background of widespread weak ascent on Thursday night suggesting disorganized but potentially widespread convection.
Friday. Mid-level dry air sweeps across the far western end of the state leaving the deepest moisture over Oahu through Maui, the eastern extent of the moisture band further displaced from evolving forcing aloft. For this reason, prefer solutions with the heavier rainfall on Friday over Maui and Oahu as opposed to the Big Island.
Friday night through Sunday. This period represents the peak of the event as forcing strengthens considerably during this period and multiple embedded shortwaves rotate around the parent trough and across the state. The rather weak area of upstream low pressure will begin to advance northeast and strengthen which will aid in the development of enhanced surface convergence and better potential for organized heavy rainfall somewhere in the central portion of the state Friday night into Saturday. Large scale forcing and moderate right entrance jet support will peak late Saturday into Sunday leading to the greatest potential for heavy rainfall. Rain rates may be particularly intense during this time. However, the upper wave digs sufficiently deep that it will usher the heavy rain band south of the Big Island by Sunday night. Thus, the peak rainfall potential will coincide with an increasingly progressive heavy rain band.
The initially weak nature of the low and subtle surface convergence features lend themselves to lower than normal forecast confidence. A Flood Watch has been issued for Oahu, Maui County, and the Big Island with the highest confidence over Oahu and Maui County at this time. Flash flood potential for Kauai is non-zero, but low confidence does not support Watch issuance there at this time. Note that saturated soils will favor increased flooding potential even though overall rainfall will not match the previous system. Finally, wind is of no concern this time around. Wind may peak in the 10-15kt range except with some higher gusts possible within deep convection. Given uncertainty surrounding this event, took a probabilistic approach to the rainfall forecast, focusing on 50th percentile values early and late and 75th percentile values during the event peak Friday night into early Sunday.
Trades return late Monday or Monday night. The lingering moisture band remains in place during this time and may provide a focus for enhanced trade wind showers over Windward Big Island during the

Aviation

VFR conditions will prevail at most locations into Thursday morning, with overnight land breezes expected at most sites. Conditions are expected to deteriorate again late Thursday into Friday as upper-level disturbance and surface low approach from the west, bringing increasing chances for widespread rainfall across portions of the state. The low-level flow will gradually veer from southeast on Thursday to south-southwest by Friday, with speeds increasing into the moderate range at exposed terminals. Expect periods of MVFR/IFR CIGS/VSBYS in showers.
AIRMET Tango is in effect for moderate turbulence for FL 200-350, due to the oncoming trough. These conditions are expected to persist through tomorrow. Will also likely include mention of light icing in layer 150-FL250 in the evening update.

Marine

Issued at 316 PM HST Wed Mar 18 2026
Light to locally moderate east to southeast winds will slowly strengthen to moderate speeds and veer south by Thursday as a ridge strengthens northeast of the state and a broad area of low pressure develops west of the state. By Friday, the low will strengthen over or near the far northwest offshore waters before lifting northeast on Saturday. Winds will shift out of the south southwest during this time at moderate speeds. Winds will become light and variable as the low shifts northeast of state with a trailing trough draped over the state. A strong high will build north of the state Sunday allowing moderate to locally strong northeast winds to return during the first half of next week.
Near shore buoys show the current moderate, medium period north swell has peaked and is trending down. Thus the High Surf Advisory has been cancelled for north facing shores of Niihau, Kauai, Oahu, Molokai and Maui. Surf along north facing shores will continue to gradually decline through Friday as the swell shifts out of the north and north- northeast. A small reinforcing pulse out of the north is expect Saturday. A new small to moderate long period west- northwest swell is expected to arrive late Saturday and hold through early next week.
Surf along south shores will see moderate surf just below High Surf Advisory (HSA) criteria as a long period south swell peaks tonight and holds through Thursday. The next small, long period south swell will fill in Saturday and peak Sunday, providing a small boost in surf along south facing shores before fading into early next week. Surf along east facing shores will remain well below average due to the lack of trades locally and upstream through the weekend. The exception will be for east facing shores

HFO Watches/Warnings/Advisories

Flood Watch from Thursday evening through Sunday afternoon for most Hawaiian Islands.
Wind Advisory until 6 AM HST Thursday for Big Island Summits.

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Data Courtesy of NOAA.gov