West Kaua’i

Today: Breezy. Mostly cloudy with showers and isolated thunderstorms. Highs around 83 near the shore to around 69 above 3000 feet. South winds 10 to 20 mph. Chance of rain 80 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible in the late evening and overnight. Lows around 70 near the shore to around 60 above 3000 feet. Southeast winds up to 15 mph. Chance of rain 80 percent.

Saturday: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs around 82 near the shore to around 68 above 3000 feet. South winds 10 to 15 mph. Chance of rain 90 percent.

South Kaua’i

Today: Mostly cloudy with showers and isolated thunderstorms. Highs 76 to 83. South winds 10 to 15 mph. Chance of rain 80 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible in the late evening and overnight. Lows around 69. Southwest winds up to 15 mph. Chance of rain 80 percent.

Saturday: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 75 to 81. Southwest winds 10 to 15 mph. Chance of rain 90 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Scattered showers and isolated thunderstorms early in the morning, then showers and isolated thunderstorms in the late morning and afternoon. Highs 71 to 83 in the valleys to around 64 above 4000 feet. Southwest winds up to 20 mph. Chance of rain 80 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible in the late evening and overnight. Lows around 67 in the valleys to around 58 above 4000 feet. Southwest winds up to 15 mph. Chance of rain 80 percent.

Saturday: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 70 to 81 in the valleys to around 61 above 4000 feet. Southwest winds up to 15 mph. Chance of rain 90 percent.

North Kaua’i

Today: Mostly cloudy. Scattered showers and isolated thunderstorms early in the morning, then showers likely and isolated thunderstorms in the late morning and afternoon. Highs 74 to 83. South winds up to 15 mph shifting to the west in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible in the late evening and overnight. Lows 63 to 71. South winds up to 15 mph. Chance of rain 80 percent.

Saturday: Mostly cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 73 to 81. Southwest winds up to 15 mph. Chance of rain 90 percent.

East Kaua’i

Today: Mostly cloudy. Scattered showers and isolated thunderstorms early in the morning, then showers likely and isolated thunderstorms in the late morning and afternoon. Highs 72 to 83. South winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible in the late evening and overnight. Lows 65 to 73. Southwest winds up to 15 mph. Chance of rain 80 percent.

Saturday: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 70 to 81. Southwest winds 10 to 15 mph. Chance of rain 90 percent.

Detailed Forecast

Synopsis

In the big picture, two surface low pressure systems will move slowly northeastward through the northern Hawaii region into the weekend, producing additional periods of moderate to heavy rain, thunderstorms, and elevated threats for flash flooding. A combination of low level forcing and passing upper level troughs will drive these smaller scale heavy rain band and thunderstorm formations. Additional weather threats include strengthening south to southwest kona winds on Saturday that will produce down sloping wind gusts in the 30 to 45 MPH range along steep north and east slopes of island mountain ranges lasting through Saturday night. Improving weather trends will develop from west to east on Monday as we transition to a wet trade wind weather pattern lasting through the end of next week.

Short term update

Issued at 913 AM HST Fri Mar 20 2026
Ongoing severe flooding this morning, especially in northern Oahu. The Wahiawa Reservoir is in danger of overtopping the dam, and a warning for dam failure (not occurring yet, but could happen soon) has been issued in coordination with local dam authorities. Radar shows showers, many heavy, continuing across the state. The heaviest showers are currently over Oahu. The axis of heaviest precipitation is expected to expand east today and tonight, spreading over Maui County while also remaining over Oahu. The flood watch will obviously be continued. No update is needed to the forecast at this time.

Prev discussion

A large slow moving band of heavy showers and thunderstorms has produced 5 to 10 inches of rainfall over the past 6 hours across the northern half of Oahu, widespread catastrophic flooding is occurring. Travel in and out of Haleiwa has been cut off due to high flood waters in the area.
The satellite and radar imagery this morning shows a slow moving band of heavy showers and thunderstorms over northern Oahu that brought widespread flooding to the northern half of the island continues to drift eastward. A few showers are back building over the island with additional rainfall rates in the 1 to 2 inches per hour range. This mesoscale convective system are passing north of the islands in Maui County this morning. However, we will need to closely monitor the track of this slow moving system for possible flooding threats to both islands as it continues to drift east through the Hawaii region.
Upper level troughing and a subtropical jet stream north of the islands continues to provide divergence aloft to help trigger heavier showers and a few thunderstorms over the next 24 hours. Threats for heavy showers and flooding will increase across the state into Saturday with the kona low drifting closer to Kauai. A combination of low level forcing and passing upper level troughs will drive these smaller scale heavy rain band and thunderstorm formation. Some of these thunderstorms may become severe as wind shear and strong instability may lead to rotating strong thunderstorms producing damaging wind gusts and heavy rain threats. The latest weather model guidance remains fairly consistent with this kona low, increasing our confidence of an extended period of moderate to heavy rain falling across the state along with periods of thunderstorms lasting into Sunday. A Flood Watch remains in effect for all Hawaiian Islands through Sunday afternoon.
Additional threats include strengthening south to southwest kona winds on Saturday that will produce down sloping wind gusts in the 30 to 45 MPH range along steep north and east slopes of island mountain ranges lasting through Saturday night. These strong wind gusts will likely uproot trees, as roots give way under saturated ground conditions, tree branches will break and fall, potentially producing another round of power outages for some local island communities.
Periods of icing and snowfall on the Big Island summits are possible above 12,000 feet elevation level along with strong gusty winds during the Saturday night through Sunday time period.
Improving weather trends will develop from west to east on Monday as we transition to a cool, wet and breezy trade wind weather pattern lasting through the end of next week.

Aviation

Conditions have deteriorated across the state as bands of rain with embedded heavy showers and storms develop and move through. These rainbands are producing periods of IFR to LIFR CIGS/VSBYS, which will persist in the weekend as an upper trough approaches from the west.
Low-level winds will continue to veer to the south-southwest and strengthen, especially at exposed terminals. These winds may result in localized mechanical turbulence leeward of terrain.
AIRMET Sierra for mountain obscuration is now in effect across all islands and will likely continue into the weekend. AIRMET Zulu for light icing in the 130-FL260 layer will continue to be a concern within deeper cloud layers associated with the upper disturbance.

Marine

Light to moderate southerly winds will strengthen tonight as surface low pressure roughly 300 nm west of Kauai and an associated front stretching north of the state deepen. Moderate to locally strong south to southwest winds will prevail Friday and Saturday, and periods of heavy showers and thunderstorms are expected. The low will lift to the north of the state on Sunday, likely allowing moderate northerly winds and lower chances for rainfall to develop around Kauai. On Monday, high pressure building north of the state will push a surface trough eastward over the islands. Fresh to strong northeast winds may require a Small Craft Advisory (SCA) over most waters, though variable winds could linger around the Big Island through the day. Fresh to potentially strong trade winds will persist on Tuesday.
Buoys are showing the north swell is a bit larger than expected at around 5 feet 11 seconds, and this swell is only expected to increase through the day and into Saturday, which will keep moderate swell going through the weekend along north facing shores. A small, overlapping west-northwest swell is expected to arrive late Saturday and hold into Monday as well. Aside from areas exposed to wrapping north swell, surf along east facing shores will remain well below average through the weekend. Early next week, the development of northeasterly trade winds could bring a potentially larger pulse of medium period north-northeast swell. This will allow rough surf to return to east facing shores, which may approach High Surf Advisory level.
A moderate south swell will slowly diminish today, followed by a small reinforcing south-southwest swell this weekend into Monday. Smaller surf is expected along south facing shores through the remainder of the week.

HFO Watches/Warnings/Advisories

Flood Watch through Sunday afternoon for Big Island East, Big Island Interior, Big Island North, Big Island South, Big Island Southeast, Central Oahu, East Honolulu, Ewa Plain, Haleakala Summit, Honolulu Metro, Kahoolawe, Kauai East, Kauai Mountains, Kauai North, Kauai South, Kauai Southwest, Kipahulu, Kohala, Kona, Koolau Leeward, Koolau Windward, Lanai Leeward, Lanai Mauka, Lanai South, Lanai Windward, Maui Central Valley North, Maui Central Valley South, Maui Leeward West, Maui Windward West, Molokai Leeward South, Molokai North, Molokai Southeast, Molokai West, Molokai Windward, Niihau, Oahu North Shore, Olomana, South Haleakala, South Maui/Upcountry, Waianae Coast, Waianae Mountains, Windward Haleakala.

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Data Courtesy of NOAA.gov