An increasingly active weather pattern unfolding across the Hawaiian Islands will persist through Friday as low pressure strengthens northwest of the state. Deep tropical moisture being drawn northward into the islands will support periods of heavy rainfall, strong southerly winds, isolated strong to severe thunderstorms through Friday. Although some brief improvement for portions of the state is possible by Saturday, another active period appears possible from Sunday through early next week.
Issued at 918 AM HST Thu Apr 9 2026
Shower activity continues this morning across the islands. Latest radar imagery shows a broad expanse of showers moving in from the southwest. A heavier band of showers is expected to move through Kauai today, spreading eastward across the islands through the overnight hours heading into Friday. With this band, gusty winds from the south will occur, making for periods of IFR or worse conditions under heavy showers and even isolated thunderstorms. Preceding the heavier rain band, expect MVFR conditions as light rain and low ceilings prevail across the islands.
AIRMET Sierra remains in effect for mountain obscuration above 020 ft across all islands. Some relief is possible as showers decrease in coverage this morning, but confidence in exact timing is low, so expect Sierra to persist through the TAF period.
AIRMET Tango also is in effect for moderate turbulence between FL200 and FL350 across the entire islands, and for moderate turbulence downwind of terrain for Oahu and Kauai. This is also expected to remain in effect through the TAF period.
AIRMET Zulu is also in effect for moderate icing between 140-FL200 as this ongoing weather pattern envelops the islands with extensive cloud cover. Expect this to remain in effect through the period as well.
Issued at 346 AM HST Thu Apr 9 2026
South to southeast winds are expected to steadily increase to strong to gale force speeds later this morning through tonight, as a low pressure system develops just west of the state and lifts northward. A Gale Warning has been issued for the western half of the coastal waters and the offshore waters due to the strengthening winds today. Small Craft Advisory (SCA) is in effect for most of the remaining waters for today.
For tonight, Gales are expected to continue over the western half of the coastal waters through the first half of the night then gradually shift eastward throughout the night. A Gale Watch remains in effect for the eastern half of the coastal waters. As the low pressure system further deepens today into Friday, we will likely see a greater coverage of thunderstorms and gusty winds especially tonight into Friday, where we could potentially see severe thunderstorms over the coastal waters capable of producing waterspouts and damaging winds. Very rough boating conditions are also expected later today into Friday as seas quickly rise in response to the strong to gale force winds. South facing harbor entrances will also be greatly impacted due to rough conditions.
The current south swell that peaked during the day yesterday has dropped below advisory thresholds this morning. But due to the strong to gale force southerly winds that are expected to quickly develop today over the western half of the state, a High Surf Advisory remains in effect for Kauai County and Oahu through tonight. Large disorganized surf is expected along south facing shores of Kauai and Oahu through at least tonight. Depending on how the low pressure system evolves today, the High Surf Advisory may need to be expanded towards Maui County tonight.
Along north facing shores, a moderate long-period northwest (310-320 degree) swell peaked during the day yesterday and will steadily lower today and dissipate to background levels on Friday. However a smaller short-period northwest swell generated by the low developing just west of us will fill in over the weekend into early next week.
Surf along east facing shores could see an increase later this week due to the strengthening southeasterly winds especially for southeast exposures.
Flood Watch through Friday afternoon for all Hawaiian islands.
High Surf Advisory until 6 AM HST Friday for East Honolulu-Ewa Plain-Honolulu Metro-Kauai South-Kauai Southwest-Niihau-Waianae Coast.
High Wind Warning until 6 AM HST Friday for Central Oahu-Kauai Mountains-Kauai North-Koolau Leeward-Koolau Windward-Oahu North Shore-Olomana-Waianae Mountains.
Winter Weather Advisory until 6 AM HST Friday for Big Island Summits.
Wind Advisory until 6 PM HST Friday for Big Island Summits.
Gale Warning until 6 AM HST Friday for Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.
Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Maui County Leeward Waters-Maui County Windward Waters.
Gale Watch from 6 PM HST this evening through Friday afternoon for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters-Big Island Windward Waters-Kaiwi Channel- Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Pailolo Channel.
