An approaching disturbance aloft combined with ample moisture and a surface trough moving over the western end of the state have triggered heavy showers and isolated thunderstorms over Kauai and Niihau and may impact Oahu overnight. The tail end of a front will move down the island chain late Sunday through Monday, bringing breezy northeasterly trades and drier air in its wake. Breezy easterly trades will bring periods of windward and mauka showers through the rest of the week.
Scattered showers currently between Kauai and Oahu will start to push towards PHNL and PHJR (and the rest of Oahu) over the next couple of hours. Persistent MVFR and some IFR ceilings and visibilities are possible in the heavier showers. If these hold together, they could affect Molokai, Lanai, and Maui by morning.
AIRMET Sierra remains in effect for IFR conditions on Kauai which may need to be extended into Oahu. AIRMET Sierra is also in effect for mountain obscuration on Oahu and windward areas of the Big Island due to low ceilings and reduced visibility in showers.
Issued at 404 PM HST Sat Oct 31 2026 A High Surf Advisory has been posted for north and west facing shores due to an incoming northwest swell. Additionally, a Small Craft Advisory has been issued for all coastal waters due to increasing winds and seas.
A trough to the northwest of Kauai will sink southward overnight, allowing high pressure to the north to strengthen winds behind the trough over the region. An incoming north-northwest (330 degrees) swell will push seas in excess of 10 feet for exposed waters, and the strengthening winds will bring SCA level winds to additional areas. Moderate to fresh northeast trades are expected to continue through much of the week.
The forerunners from the new moderate, long-period northwest swell are expected to arrive in the next couple of hours, with the swell building quickly overnight. By Sunday, advisory level surf is expected for north and west facing shores, which is expected to continue into Monday. The swell may shift to a slightly more northerly direction on Monday before declining on Tuesday. Depending on the exact direction, a Marine Weather Statement may be issued for potential harbor surges at Kahului and Hilo during that time. Another advisory level northwest swell is possible Thursday into Friday.
The current moderate, medium period south swell will gradually decline through the weekend. Surf above seasonal average returns to seasonal average on Sunday as the south swell energy fades. During the first half of next week, south shore surf will return to below seasonal averages.
East-facing shores will see an increase in trade wind swell as northeast winds return on Sunday. Surf along east-facing shores will increase through Monday night and conditions will be choppy as trades sustain through much of the week.
High Surf Advisory from 6 AM Sunday to 6 PM HST Monday for Kauai East-Kauai North-Kauai Southwest-Koolau Windward-Maui Central Valley North-Maui Windward West-Molokai North-Molokai Windward- Niihau-Oahu North Shore-Waianae Coast-Windward Haleakala.
Small Craft Advisory from 6 AM Sunday to 6 PM HST Monday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters-Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters-Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters- Pailolo Channel.
