textproduct: Honolulu

SYNOPSIS

Trade winds will steadily strengthen today and a wind advisory remains in effect for areas of Maui County and Big Island through tonight. Passing showers will continue to move in on breezy to windy trade winds through next week. As usual, these showers will be most frequent during the nights and early morning hours across windward and mauka areas.

UPDATE

The breezy to locally windy forecast remains on track. A High Surf Advisory has been issued for east facing shores due to rough surf generated by the increasing trades.

PREV DISCUSSION

Issued at 403 AM HST Thu May 21 2026 This morning's radar and satellite imagery shows scattered showers riding in with the breezy to windy trade winds mainly over windward and mauka areas. Rainfall totals over the past 24 hours have varied quite a bit of rainfall amounts of up to 1 to 2 inches at the wettest areas. 12Z soundings from Lihue and Hilo continues to show an elevated inversion, which explains the higher rainfall amounts. As we go through the day today and into tonight, drier air aloft should really fill in tonight, which should cause the trade wind inversion to strengthen and lower. This will result in the winds becoming more gusty later this afternoon into tonight. Wind gusts in the 50 mph range has been measured at the windier areas of Maui County and the Big Island, where we have a Wind Advisory in effect through tonight. The Wind Advisory may have to be extended through Friday. While we don't have a Wind Advisory for Oahu, we could see wind gusts near advisory thresholds later this afternoon into tonight for select valleys downwind of terrain such as Manoa Valley.

While the drier air aloft should help lower rainfall amounts later tonight, strong orographic lifting from the windy trade winds will continue to produce scattered showers over windward and mauka areas.

For the weekend, windy conditions will likely continue through Saturday. Trade winds could drop a notch on Sunday, but nonetheless breezy to strong trades will likely continue through early next week. Passing showers will continue to ride in with the strong trades especially during the night and early morning hours. Shower coverage could slightly increase towards the first half of next week as we see a subtle increase of low level moisture.

AVIATION

A tight pressure gradient back across the islands from high pressure north northeast of the state will produce fresh to strong trade winds through tomorrow. Greater stability from upper ridging expanding in from the north and west, along with drier air filling in from the northeast, will result in less frequent shower behavior. The bulk of the shower activity will impact windward higher terrain, especially during the evening and early morning hours.

AIRMET Sierra is in effect this morning for mountain obscuration across windward portions of Kauai, Molokai, Maui and Big Island. AIRMET Tango is in place for low level turbulence over and downwind of terrain. This AIRMET will remain in place for the next couple of days in response to strengthened winds and higher stability.

MARINE

The strong high pressure ridge north of the Hawaiian Islands will maintain easterly trade winds in the strong to gale range through Friday morning. A Gale Warning remains in effect for the Alenuihaha and Pailolo Channels, and Maalaea Bay and a Small Craft Advisory (SCA) for all remaining island waters. Expect SCA to continue into the first half of next week.

A high surf advisory (HSA) has been issued for all east facing shores through Friday afternoon due to strong trade wind swell building through the day. Winds may ease a touch tonight allowing surf to drop below advisory levels Friday afternoon through the weekend but conditions will remain borderline and thus will continue to monitor in case there is a need to extend the HSA.

Small, short to medium period north-northwest (330 degree) swell energy will decline today. The next small north-northwest (330 degree) swell will move into the Hawaii region on Saturday, increasing surf heights along north and west-facing shores through the weekend.

A series of small, long-period south swells will support near- average surf along south-facing shores over the next several days.

HFO WATCHES/WARNINGS/ADVISORIES

High Surf Advisory until 6 PM HST Friday for Big Island East-Big Island North-Big Island Southeast-East Honolulu-Kahoolawe-Kauai East-Kauai North-Kipahulu-Koolau Windward-Maui Windward West- Molokai Southeast-Molokai Windward-Olomana-South Haleakala- Windward Haleakala.

Wind Advisory until 6 AM HST Friday for Big Island North-Big Island South-Big Island Southeast-Kahoolawe-Kohala-Lanai Leeward- Lanai Mauka-Lanai South-Lanai Windward-Maui Central Valley North- Maui Central Valley South-Maui Leeward West-Maui Windward West- Molokai Leeward South-Molokai North-Molokai Southeast-Molokai West-Molokai Windward-South Haleakala.

Small Craft Advisory until 6 AM HST Friday for 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-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.

Gale Warning until 6 AM HST Friday for Alenuihaha Channel- Maalaea Bay-Pailolo Channel.