Hilo

Tonight: Cloudy. Showers likely early in the evening, then isolated showers in the late evening and overnight. Isolated thunderstorms after midnight. Lows 63 to 70 near the shore to 53 to 59 at 4000 feet. South winds around 10 mph. Chance of rain 70 percent.

Friday: Mostly cloudy with isolated showers and thunderstorms. Highs 77 to 83 near the shore to around 67 at 4000 feet. South winds around 10 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy with isolated showers and thunderstorms. Lows 63 to 70 near the shore to 54 to 60 at 4000 feet. South winds around 10 mph. Chance of rain 20 percent.

Kona

Tonight: Showers early in the evening, then scattered showers in the late evening and overnight. Isolated thunderstorms after midnight. Lows around 72 near the shore to 50 to 56 near 5000 feet. Southeast winds around 10 mph. Chance of rain near 100 percent.

Friday: Mostly cloudy. Scattered showers and isolated thunderstorms early in the morning, then isolated showers and thunderstorms in the late morning and afternoon. Highs 81 to 86 near the shore to around 67 near 5000 feet. South winds 10 to 15 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy with isolated showers and thunderstorms. Lows around 73 near the shore to 50 to 56 near 5000 feet. South winds around 10 mph. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy. Isolated showers in the evening, then isolated showers and thunderstorms after midnight. Lows 63 to 70 near the shore to 58 to 63 near 3000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly cloudy. Isolated showers and thunderstorms early in the morning, then scattered showers and isolated thunderstorms in the late morning and afternoon. Highs 74 to 80 near the shore to 69 to 75 near 3000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy with scattered showers and isolated thunderstorms. Lows 63 to 71 near the shore to 58 to 63 near 3000 feet. Light winds. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy. Isolated showers in the evening, then isolated showers and thunderstorms after midnight. Lows 63 to 70 near the shore to 58 to 63 near 3000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly cloudy. Isolated showers and thunderstorms early in the morning, then scattered showers and isolated thunderstorms in the late morning and afternoon. Highs 74 to 80 near the shore to 69 to 75 near 3000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy with scattered showers and isolated thunderstorms. Lows 63 to 71 near the shore to 58 to 63 near 3000 feet. Light winds. Chance of rain 50 percent.

South Big Island

Tonight: Showers in the evening, then showers and isolated thunderstorms after midnight. Lows around 74 near the shore to around 55 near 5000 feet. East winds around 10 mph. Chance of rain near 100 percent.

Friday: Mostly cloudy. Showers and isolated thunderstorms early in the morning, then isolated showers and thunderstorms in the late morning and afternoon. Highs around 83 near the shore to around 65 near 5000 feet. Southeast winds 10 to 15 mph. Chance of rain 80 percent.

Friday Night: Mostly cloudy with isolated showers and thunderstorms. Lows around 74 near the shore to around 55 near 5000 feet. Southeast winds around 10 mph. Chance of rain 20 percent.

Puna

Tonight: Cloudy. Showers likely early in the evening, then isolated showers in the late evening and overnight. Isolated thunderstorms after midnight. Lows 63 to 70 near the shore to 53 to 59 at 4000 feet. South winds around 10 mph. Chance of rain 70 percent.

Friday: Mostly cloudy with isolated showers and thunderstorms. Highs 77 to 83 near the shore to around 67 at 4000 feet. South winds around 10 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy with isolated showers and thunderstorms. Lows 63 to 70 near the shore to 54 to 60 at 4000 feet. South winds around 10 mph. Chance of rain 20 percent.

Waikoloa

Tonight: Showers early in the evening, then isolated showers in the late evening and overnight. Isolated thunderstorms after midnight. Lows around 73 near the shore to 52 to 58 above 4000 feet. Southwest winds around 10 mph shifting to the southeast after midnight. Chance of rain near 100 percent.

Friday: Mostly cloudy. Isolated showers and thunderstorms early in the morning, then showers and isolated thunderstorms in the late morning and afternoon. Highs 81 to 86 near the shore to 65 to 70 above 4000 feet. West winds 10 to 15 mph. Chance of rain 90 percent.

Friday Night: Cloudy with scattered showers and isolated thunderstorms. Lows around 74 near the shore to 53 to 58 above 4000 feet. West winds around 10 mph shifting to the south after midnight. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Two surface low pressure systems will move slowly northeastward through the northern Hawaii region into the weekend, producing 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 formation. 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

Looking into the satellite picture this evening we see a small scale convergence boundary located in the Kauai Channel between Kauai and Oahu. This boundary continues to produce areas of heavy showers and will slowly drift eastward towards Oahu through the overnight hours. A subtropical jet stream north of the islands continues to provide divergence aloft to help trigger these heavier showers and possible thunderstorms over the next 12 to 24 hours. The threats for heavy showers and flooding will increase as we move into Friday with a surface 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.
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.

Previous discussion

Issued at 301 PM HST Thu Mar 19 2026
Large scale forcing generally neutral at press time this afternoon with little change in the mid-level height field during the last 12 hours and weak subsidence aloft courtesy of the right exit of the resident upper jet. Little in the way of persistent convergence exists at the surface leads to a nebulous forecast scenario in which identifiable features supporting organization remain evasive. Weak isentropic ascent within SW moist mid-level flow has supported waves of elevated light/moderate stratiform rainfall across the state today. At the same time, southeast boundary layer flow wrapping around the Big Island has steered heavier surface-based showers over Kauai, Oahu, and the western portion of Maui County. Maui itself appears to be shadowed within this pattern of low-level SE flow. Rainfall amounts generally around a quarter of an inch for Oahu and one half to one inch for Kauai.
For tonight into Friday, there is atypically high uncertainty for such a short lead time. As upstream low pressure slowly evolves, boundary layer flow will veer to a more S/SW direction allowing boundary layer showers to spread over Maui this evening. Surface convergence then likely results in an increasingly organized band of moderate to heavy showers that could be a persistent feature through much or all of Friday. However, the weak nature of the surface low is causing models to contend with surface pressure falls resulting from downstream convection. This in turns leads to radically different low-level flow solutions during the next 24 hours in an environment in which identifying low-level convergence is crucial. The EC allows a secondary low to form downstream due to convective influences and attendant surface convergence supports persistent convection over Maui County as soon as 8pm HST this evening. The GFS maintains a more persistent and weak parent low and convergence takes more time to develop, but when it does it sets up over Kauai during Friday. The HRRR focuses convection directly over Oahu through tonight.
21z ASCAT showed well defined surface convergence about 320 miles west of Kauai which is evident on visible imagery as a meridionally oriented cloud band. On this seemingly critical corridor of developing low-level convergence, the EC is not only an outlier among the guidance but is far too fast advancing it eastward. Among all the guidance, including the HRRR, only the UKMet appears to handle the current situation adequately. As it happens, it is also the only model to not develop secondary low pressure centers due to convection. It has been, and remains, the preferred guidance for this kona low through at least the next 24-48 hours.
Gentle ascent within moist SW flow will maintain shallow convective showers from Kauai through Maui tonight while convergence very slowly becomes established upstream. By early Friday, the UKMet indicates organizing convergence approaching Kauai supporting increased potential for organized heavy rainfall there during the day. By Friday night, large scale forcing begins to ramp up allowing heavy showers to become increasingly widespread from Kauai through Oahu and part or all of Maui County. The progressive nature of the forcing field means the uptick in intensity will coincide with increasing forward motion of the heavy rain band which helps mitigate a greater flash flooding threat. The UK then clears Kauai on Saturday night and Oahu by Sunday morning. Heavy rain then focuses over Maui County and the Big Island on Sunday, the Big Island being the last in line to receive heavy rainfall. By late Sunday, the band is likely ushered south the aggressively digging upper wave.
Breezy trades return on Monday or Monday night. With the remnant moisture band still in place over the eastern end of the state, enhanced showers are likely over Windward Big Island and/or Windward Maui Monday night into Tuesday.

Aviation

Conditions have deteriorated across the western end of the state as a broad shield of rain with embedded heavier showers has spread over Kauai and Oahu. These rainbands have produced periods of IFR to LIFR CIGS/VSBYS, and these conditions will likely persist through the overnight hours with only brief intermittent improvements.
Looking ahead through Friday, unsettled conditions will continue as the upper-level disturbance approaches from the west. The area of enhanced moisture and lift will gradually expand eastward down the island chain, leading to a continued increase in shower coverage and intensity across Maui County and the Big Island. Periods of MVFR with tempo IFR will become more widespread statewide, particularly within heavier showers or storms that develop.
Low-level winds will continue to veer to the south-southwest and strengthen into the moderate/breezy range, 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 Kauai and Oahu and will likely expand eastward overnight into Friday as clouds and showers increase. AIRMET Zulu for light icing in the 130-FL260 layer will continue to be a concern within deeper cloud layers associated with the disturbance.

Marine

Issued at 301 PM HST Thu Mar 19 2026
Light to moderate southeast 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 fresh 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 will 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.
A small, medium period north swell continues a slow decline. Nearshore PacIOOS buoys show the swell from 345-360 degrees at around 4 feet 12 seconds. The swell will drop slightly as it shifts out of the north-northeast Friday. A moderate reinforcing north-northeast swell is due Saturday and Sunday, and a small, overlapping west-northwest swell is expected to arrive late Saturday and hold into Monday. Early next week, a potentially larger pulse of medium period north-northeast swell could produce surf near the High Surf Advisory level and contribute to the need for a SCA.
Aside from areas exposed to wrapping north swell, surf along east facing shores will remain well below average through the weekend. As northeast trade winds develop early next week, rough surf will return to east facing shores, and some areas exposed to the north-northeast swell may approach the advisory level.
The south swell that produced surf around the High Surf Advisory level yesterday is on a gradual decline. The PacIOOS buoy off of Lanai shows that the swell is down to about 3 feet at 14 seconds this afternoon, with a further slow decline expected Friday. As this swell fades, a small south-southwest swell will arrive this weekend, then decline 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 all Hawaiian Islands.

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Data Courtesy of NOAA.gov