West Kaua’i

Rest Of Today: Breezy. Cloudy with scattered showers and slight chance of thunderstorms late in the morning, then partly sunny with scattered showers in the afternoon. Locally heavy rainfall possible late in the morning. Highs 85 to 91 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then scattered showers and slight chance of thunderstorms after midnight. Locally heavy rainfall possible after midnight. Lows around 73 near the shore to around 63 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny. Breezy. Slight chance of thunderstorms and isolated showers in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 85 to 90 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Kaua’i

Rest Of Today: Mostly cloudy. Breezy. Scattered showers and slight chance of thunderstorms late in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible late in the morning. Highs 81 to 90. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely and slight chance of thunderstorms after midnight. Locally heavy rainfall possible after midnight. Lows around 74. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Breezy. Numerous showers and slight chance of thunderstorms in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 81 to 89. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Rest Of Today: Cloudy. Showers likely and slight chance of thunderstorms late in the morning, then showers likely in the afternoon. Locally heavy rainfall possible late in the morning. Highs 75 to 84 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then occasional showers and slight chance of thunderstorms after midnight. Locally heavy rainfall possible after midnight. Lows 65 to 71 in the valleys to around 60 above 4000 feet. East winds up to 20 mph. Chance of rain 90 percent.

Saturday: Mostly cloudy. Breezy. Occasional showers and slight chance of thunderstorms in the morning, then numerous showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 74 to 83 in the valleys to around 66 above 4000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

North Kaua’i

Rest Of Today: Mostly cloudy. Scattered showers and slight chance of thunderstorms late in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible late in the morning. Highs 78 to 88. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely and slight chance of thunderstorms after midnight. Locally heavy rainfall possible after midnight. Lows 66 to 74. East winds up to 15 mph. Chance of rain 70 percent.

Saturday: Partly sunny. Numerous showers and slight chance of thunderstorms in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 77 to 88. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Rest Of Today: Mostly cloudy. Scattered showers and slight chance of thunderstorms late in the morning, then showers likely in the afternoon. Locally heavy rainfall possible late in the morning. Highs 74 to 86. East winds 10 to 15 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then showers likely and slight chance of thunderstorms after midnight. Locally heavy rainfall possible after midnight. Lows 66 to 77. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Numerous showers and slight chance of thunderstorms in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 74 to 86. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Update

Flood watch for Kuaui and Niihau has been cancelled as latest radar and satellite data show minimal chance for flood-producing rain over the next several hours. Heavy rain is still possible tonight with stronger showers and any thunderstorms that may develop.

Synopsis

An upper level low pressure system, currently situated a few hundred miles west of Kauai, will slowly drift to the west southwest for the next several days. Moderate to locally strong trade winds, coupled with moisture and instability associated with the low, will continue to bring enhanced showers and isolated thunderstorms to much of the state through at least Saturday. Another upper level low is forecast to drop southward towards the islands early next week and maintain an unsettled weather pattern.

Aviation

An upper level low pressure system just west of the state will continue to bring an unstable airmass with enhanced showers to the entire area today. However, these showers will be mainly focused along northeast and east portions of the islands. There will isolated thunderstorms across the affect airports on Kauai and Oahu along with areas over their adjacent coastal waters. Expect periods MVFR conditions, along with isolated IFR ceilings and visibility in some of the more robust showers and storms.
AIRMET SIERRA remains in effect for Big Island, Oahu, Kauai, Molokai, and Maui above 2000 feet for tempo mountain obscuration due to clouds and showers. SIERRA will likely continue through the remainder of the day.
AIRMET TANGO is in effect for across the island chain for tempo moderate turbulence between FL300 and FL350. This is expected to through the remainder of the day.

Marine

Moderate to locally strong trades will remain in place over the Hawaiian coastal waters through Saturday. Trade winds will weaken hold in the fresh to moderate range through early next week. An upper low north of Kauai continues to drifting southwestward into the northern coastal waters today and will keep isolated thunderstorms in the forecast over the waters into the weekend. A Small Craft Advisory (SCA) remains in effect for windier waters and channels surrounding Maui and the Big Island. The SCA was expanded to include northern coastal waters near Kauai and Oahu.
Two moderate, long period NW and NNW swells moving through the Hawaii region will keep surf heights elevated along N and W facing shores through the end of the week. Surf along N and W facing shores slowly trends down on Sunday. A hurricane force low E of Japan will bring another round of moderate, long period NW (330 deg) swell into the islands building surf heights along N and W facing shores from next Wednesday onward. This next long period swell may possibly reach low end High Surf Advisory levels from Wednesday into Thursday if we add a one to two foot upward adjustment to swell heights as compared to the ECMWF Wave model.
A series of small, medium to long period S to SW swells filter into the area into the weekend, keeping S shores from going flat. Short period surf along E shores picks up through the weekend as trade winds strengthen.

Prev discussion

/ISSUED 349 AM HST Fri Oct 17 2025/
Radar continues to indicate enhanced shower activity over mainly northeast and eastern portions of all islands and adjacent coastal waters. Overnight rainfall accumulation totals, however, have not been overly impressive with less than an inch recorded for the wettest standout locations. Unstable conditions aloft, as noted on the 12Z Lihue RAOB sounding, along with low level convergent boundaries, have aided in the development of thunderstorms just south of Oahu and north of Kauai early this morning. A Flood Watch has been issued for Kauai through noon to account for a cluster of thunderstorms north of Kauai slowly sagging to the southward. This Watch may need to be extended in time depending on the evolution of complex later today.
An upper level low, centered roughly 200 miles west of Kauai, has been responsible for the unsettled weather experienced over the past 24 hours. Both the GFS and ECMWF prog the low to drift slowly westward through Saturday. Thus, with the associated instability still in place, moderate to locally strong trades will continue to drive rounds of enhanced showers and isolated thunderstorms over the state through early this weekend. Most heavy rain and thunderstorm activity remain over Oahu, Kauai, and their surrounding coastal waters, closest to the aforementioned low. Shower activity may wane slightly Saturday morning into Sunday as the upper level feature moves further west, away from the state.
The first upper low will be replaced by a second one late Monday. This next one will stall to the northeast of the state and weaken through mid week. However, an upper trough connecting the remnants of the first low to our SW and the second one to the NE will remain over the area. This feature should help to maintain enhanced showers in a moderate to breezy trade wind pattern.
AVIATION…
An upper level low pressure system just west of the state will continue to bring an unstable airmass with enhanced showers to the entire area today. However, these showers will be mainly focused along northeast and east portions of the islands. There will isolated thunderstorms across the affect airports on Kauai and Oahu along with areas over their adjacent coastal waters. Expect periods MVFR conditions, along with isolated IFR ceilings and visibility in some of the more robust showers and storms.
AIRMET SIERRA remains in effect for Big Island, Oahu, Kauai, Molokai, and Maui above 2000 feet for tempo mountain obscuration due to clouds and showers. SIERRA will likely continue through the remainder of the day.
AIRMET TANGO is in effect for across the island chain for tempo moderate turbulence between FL300 and FL350. This is expected to through the remainder of the day.
MARINE…
Moderate to locally strong trades will remain in place over the Hawaiian coastal waters through Saturday. Trade winds will weaken hold in the fresh to moderate range through early next week. An upper low north of Kauai continues to drifting southwestward into the northern coastal waters today and will keep isolated thunderstorms in the forecast over the waters into the weekend. A Small Craft Advisory (SCA) remains in effect for windier waters and channels surrounding Maui and the Big Island. The SCA was expanded to include northern coastal waters near Kauai and Oahu.
Two moderate, long period NW and NNW swells moving through the Hawaii region will keep surf heights elevated along N and W facing shores through the end of the week. Surf along N and W facing shores slowly trends down on Sunday. A hurricane force low E of Japan will bring another round of moderate, long period NW (330 deg) swell into the islands building surf heights along N and W facing shores from next Wednesday onward. This next long period swell may possibly reach low end High Surf Advisory levels from Wednesday into Thursday if we add a one to two foot upward adjustment to swell heights as compared to the ECMWF Wave model.
A series of small, medium to long period S to SW swells filter into the area into the weekend, keeping S shores from going flat. Short period surf along E shores picks up through the weekend as trade winds strengthen.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Channel, Oahu Windward Waters.
Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.