textproduct: Honolulu

SYNOPSIS

A surface kona low pressure system continues to meander northeastward away from the Hawaiian Islands, producing bands of moderate to heavy showers and embedded isolated thunderstorms across much of the state, namely Maui County and the Big Island. As the system exits the vicinity of the islands, a broad area of high pressure fills in its wake Monday, allowing trades to return from west to east, persisting through the remainder of the week. Windward showers will initially be scattered to numerous Monday, but will decrease to a more typical trade wind regime with isolated to scattered showers across windward and mauka areas.

SHORT TERM UPDATE

Issued at 840 AM HST Sun Mar 22 2026

The forecast remains on track with the focus of heavy showers and isolated thunderstorms across Maui County and Big Island associated with the kona low. Rainfall across Big Island remains loosely organized, whereas a band of showers and thunderstorms is situated over Maui County. The Flood Watch remains in effect for Oahu, Maui County, and Big Island at this time as a result. Outside of the showers, winds remain light across the region.

MARINE

Bands of moderate to heavy showers, with an occasional embedded thunderstorm, will primarily impact the waters surrounding Maui County and Big Island through Monday. A boundary will pass across the waters from the north through Monday. Gentle variable to southerly breezes will swing north northeast and strengthen to moderate speeds through Monday. Moderate trades will become better re-established early this week with widely scattered light showers as the upper trough passes east of the waters by Tuesday morning.

Northeast swell that peaked yesterday will be on the decline through Monday. Another small north swell that peaked earlier today will reinforce north swell and maintain elevated north- facing shore surf today. Background south southwest swell will maintain small south-facing shore surf through the remainder of the week. East-facing shore surf will stay slightly elevated today due to the fading northeast swell and some lingering north wrap. Eastern surf will fall off a touch today with the lowering swell but wind wave chop will pick back up at mid week in response to strengthened trades.

PREV DISCUSSION

/ISSUED 319 AM HST Sun Mar 22 2026/

Latest observations indicate a broad band of showers and embedded isolated thunderstorms persisting over Maui County, gradually shifting eastward toward the Big Island. Additionally, smaller bands of showers have developed south of the Big Island near South Point, as well as across the coastal waters between Kauai and Oahu.

The upper-level trough and associated surface kona low remain positioned north of the Hawaiian Islands and continue to drift northeastward away from the state while gradually weakening. Despite this trend, lingering moisture and instability will support continue shower activity across the islands through this evening, with the greatest coverage over Maui County and the Big Island and more scattered activity elsewhere. As a result, the Flash Flood Watch remains in effect for Oahu, Maui County, and the Big Island through 6 PM this evening. Furthermore, the Winter Storm Warning remains in effect for the Big Island summits through 6 PM this evening as well.

In the wake of this departing system, a broad area of high pressure will build into the region, signaling a transition back to a more typical trade wind pattern. Trade winds are expected to return to the western islands as early as Monday, spreading to the eastern end of the state by Monday night. Residual low-level moisture associated with the kona storm will shift into a more typical trade wind distribution, favoring windward and mauka areas. Locally numerous showers may persist along windward Big Island into Monday night. By Tuesday, a more typical trade wind regime is expected statewide, with isolated to scattered showers primarily affecting windward and mauka areas. This pattern is expected through the remainder of the forecast period.

AVIATION

Bands of showers and embedded isolated thunderstorms continue to move over Maui County and the Big Island. The ongoing kona low will support further rain bands, mainly across Maui County and the Big Island, and to a lesser extent on Oahu. Winds will remain primarily out of the south to southwest until late today. This evening, trades will begin spreading back into the state from west to east. Expect widespread MVFR conditions over the eastern end of the state through sometime Monday, with locally LIFR conditions under showers and any thunderstorms.

AIRMET Sierra is in effect for Molokai, Maui, and Lanai due to IFR in widespread low ceilings and showers and is expected to continue through the afternoon. AIRMET Sierra is also in effect for Oahu and the Big Island due to mountain obscuration due to showers and low clouds. This is also expected to continue through the afternoon.

AIRMET Zulu remains for light icing in layer 140-FL260 will also persist, mainly over the central portion of the state where the thick high clouds continue to stream over from the southwest.

HFO WATCHES/WARNINGS/ADVISORIES

Flood Watch until 6 PM HST this evening for Waianae Coast-Oahu North Shore-Olomana-Central Oahu-Waianae Mountains-Lanai Mauka- Kahoolawe-Maui Windward West-Maui Leeward West-Haleakala Summit- Kona-Kohala-Big Island Interior-East Honolulu-Honolulu Metro-Ewa Plain-Koolau Windward-Koolau Leeward-Molokai-Lanai Windward- Lanai Leeward-Lanai South-Maui Central Valley North-Maui Central Valley South-Windward Haleakala-Kipahulu-South Maui/Upcountry- South Haleakala-Big Island South-Big Island Southeast-Big Island East-Big Island North.

Winter Storm Warning until 6 PM HST this evening for Big Island Summits.