West Kaua’i

Rest Of Today: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs around 79 near the shore to around 67 above 3000 feet. Light winds. Chance of rain 90 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Lows around 67 near the shore to around 58 above 3000 feet. Light winds. Chance of rain 90 percent.

Monday: Cloudy. Showers and isolated thunderstorms early in the morning, then scattered showers in the late morning and afternoon. Locally heavy rainfall possible early in the morning. Highs around 82 near the shore to around 70 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 80 percent.

South Kaua’i

Rest Of Today: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 73 to 79. Light winds. Chance of rain 90 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Lows around 67. Northeast winds up to 10 mph increasing to 10 to 15 mph after midnight. Chance of rain 90 percent.

Monday: Cloudy. Showers and isolated thunderstorms early in the morning, then showers likely in the late morning and afternoon. Locally heavy rainfall possible early in the morning. Highs 77 to 82. Northeast winds 10 to 15 mph in the morning becoming light. Chance of rain 80 percent.

Kaua’i Mountains

Rest Of Today: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 69 to 74 in the valleys to around 61 above 4000 feet. Light winds. Chance of rain 90 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Lows 60 to 66 in the valleys to around 57 above 4000 feet. Light winds. Chance of rain 90 percent.

Monday: Cloudy. Showers and isolated thunderstorms early in the morning, then showers likely in the late morning and afternoon. Locally heavy rainfall possible early in the morning. Highs 73 to 79 in the valleys to around 63 above 4000 feet. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 80 percent.

North Kaua’i

Rest Of Today: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 70 to 78. Light winds. Chance of rain 90 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Lows 61 to 69. Light winds becoming southeast up to 15 mph after midnight. Chance of rain 90 percent.

Monday: Cloudy. Showers and isolated thunderstorms early in the morning, then scattered showers in the late morning and afternoon. Locally heavy rainfall possible early in the morning. Highs 73 to 81. South winds up to 15 mph in the morning becoming light. Chance of rain 80 percent.

East Kaua’i

Rest Of Today: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 68 to 78. Light winds. Chance of rain 90 percent.

Tonight: Cloudy with showers and isolated thunderstorms. Locally heavy rainfall possible. Lows 62 to 70. Light winds. Chance of rain 90 percent.

Monday: Cloudy. Showers and isolated thunderstorms early in the morning, then showers likely in the late morning and afternoon. Locally heavy rainfall possible early in the morning. Highs 71 to 81. South winds up to 10 mph. Chance of rain 80 percent.

Detailed Forecast

Synopsis

Showers will continue for the entire day over Kauai and Oahu with the heaviest rain and greatest flooding potential over Oahu. LIght trades return at the end of the week.

Short term update

Issued at 834 AM HST Sun Apr 12 2026
Limited instability on this mornings Lihue sounding indicative of the very warm, saturated, and poor lapse rate environment in place over the islands. Radar imagery matches forecast expectations well with decaying rainfall over Kauai and developing showers poised to spread across Oahu and possibly Molokai this morning. As expected, guidance still indicates low-level convergence draped over Oahu for much of the day. This is related to the deep tropospheric frontal structure tied to strengthening right entrance jet dynamics aloft. However, this has yet to bear out on radar with no discernible organization evident so far. Instead, the rain shield is broad and stratiform in nature with convective elements that so far are struggling to produce even 1″ per hour. Given that Oahu is lined up to receive about 15-18 hours of nearly uninterrupted rainfall, rain rates are the only thing standing between routine flood impacts and a much more serious flash flooding situation. However, at this time there does not appear to be any reason to expect rates to increase as instability is essentially nil and forcing does not change in type or magnitude at any point. Perhaps low-level convergence materializes and supports a period of higher rates or localized/brief 1-2″/hr rates within transient convective cells advance over the island, but as of this morning this event appears to be a 0.5″/hr low rate grinder with several inches of rain spread over many hours. Of note, the Flood Watch remains in effect for the Big Island to cover convective potential mainly over the South Kohala and North Kona Districts this afternoon.

Aviation

Issued at 834 AM HST Sun Apr 12 2026
An unstable band of deep tropical moisture will move up from the south under an upper level disturbance. Weather conditions will destabilize today, producing widespread MVFR and isolated IFR conditions statewide with low clouds, showers and isolated thunderstorms from early this morning through early Monday morning. Oahu is expected to be the most likely to receive periodic heavy showers. Light land-sea breezes less than 10 kts will prevail across all sites.
AIRMET Sierra remains in effect for mountain obscuration above 1500 ft for Kauai and Oahu, as well as for IFR conditions at Molokai, Lanai, and Maui. These conditions are expected to remain today with the oncoming shower threat, with some relief expected later this evening as conditions dry out, however low clouds may remain due to light winds and lingering moisture.
Widespread cloud cover over the state today may also lead to moderate icing.

Marine

A surface trough will linger in the vicinity of the central islands into early next week, keeping moderate to fresh southeasterly winds to its east, and light and variable winds to its west. This weak surface boundary along with an upper level disturbance moving into the region brings another round of showers and isolated thunderstorms today into Monday. As the surface trough lifts north and high pressure to the northeast begins to takes over at the surface, gentle to moderate easterly trades will gradually develop across the Hawaiian coastal waters by the end of next week.
A moderate, short to medium-period north-northwest swell (340 degrees) generated by the formerly-gale force low north-northwest of the main Hawaiian islands arrives along north and west facing shores today. This will maintain small to moderate surf through the beginning of the week, followed by a decline in northwest swell energy for the rest of the week.
A medium-period south swell will continue to decline through Monday. By Tuesday, however, a new south swell will arrive, once again providing a boost to surf along south facing shores through mid week before gradually subsiding into the weekend.
Surf along east facing shores remains below seasonal average with lighter than average trade winds near and upstream of the islands forecast through next week.

HFO Watches/Warnings/Advisories

Flood Watch through Monday afternoon for Hawaii.

Data Courtesy of NOAA.gov