textproduct: Honolulu

SYNOPSIS

A high pressure system far north of the Hawaiian Islands will slowly drift east, however a broad ridge north of the region will remain in place keeping easterly trade winds in the forecast through into next weekend. An upper level trough approaching the islands on Monday will deepen into an upper low near Kauai by Tuesday, leading to increasing cloud and shower trends across the region through the week. Shower activity will favor windward mountain areas in the overnight to early morning hours with brief periods of showers drifting into leeward areas.

SHORT TERM UPDATE

Bands of unsettled showers along the eastern edge of a departing low level trough are shown on satellite imagery this evening. Expect periods of passing showers mainly along windward mountains through the morning hours with slight decreasing shower coverage trends during the day. Easterly trade winds with periods of windward mountain showers will continue into next weekend.

The current forecast grids look reasonable, no evening updates.

PREVIOUS DISCUSSION

Issued at 353 PM HST Sun Apr 26 2026 This afternoon, radar and satellite show clouds and showers focused on windward and mauka areas. The strongest showers were over the Kau District on the Big Island. Other more consistent showers were over windward Maui.

The upper level pattern north of the islands will carry a series of troughs west to east across the Pacific Ocean through the next week, but for the most part these will be too far north to bring a significant change to the weather at the surface here in Hawaii. The lone exception will be a small and relatively weak closed low that is expected to form just to the northeast of the state late Tuesday. This low will then slowly track ENE away from the state through next weekend. Overall, the region will remain under the influence of ridging aloft to our WNW (centered around 25 deg N).

This upper low will not be strong enough to prevent trades from continuing at the surface, but it will bring a little more instability aloft, and therefore we may see some stronger showers Tuesday through Friday. Showers will remain mainly windward and mauka, and more numerous at night for most areas. Afternoon kona showers, along with showers over the peaks of the Big Island, will remain in the forecast as well. Finally, from the middle of next week into next weekend, trades will become a stronger.

AVIATION

Moderate trades will continue through the period. Intermittent MVFR is possible across windward sites due to low cigs and showers, but VFR conditions are broadly anticipated. Shower activity may ramp up starting around sunset Monday as an upper- level system moves toward the islands.

No AIRMETs are in effect, however a mountain obscuration AIRMET may be needed if low clouds become more widespread due to oncoming shower activity.

MARINE

Issued at 353 PM HST Sun Apr 26 2026 Easterly trade winds have eased slightly compared to the past couple of days as a weak surface trough moves through the region from east to west. Guidance indicates trades will strengthen somewhat tonight and Monday, with borderline Small Craft Advisory-level winds possible in the typically windier waters surrounding Maui County and the Big Island. Winds look to strengthen more significantly by mid-week as strong high pressure rebuilds far north of the state, with increased confidence for advisory-level winds, potentially including additional coastal waters.

Surf along north-facing shores will begin to gradually ease tonight into the first half of the week as the offshore buoy 51001 (to the northwest) shows decreasing medium-period swell energy over the past several hours. An upward trend is expected during the second half of the week as swell generated by a broad low near the Aleutians reaches Hawaii. Looking farther ahead, a storm- force low developing east of Japan on Monday looks to direct a longer-period northwest swell toward the islands for Friday and Saturday, with surf heights potentially approaching advisory levels along exposed north and west facing shores.

Surf along south-facing shores will remain somewhat inconsistent as a southwest swell peaks this evening/tonight. This will be followed by a gradual downward trend on Monday. Another small south-southwest pulse may arrive next weekend from activity within our swell window east of New Zealand.

Surf along east facing shores will remain relatively small and choppy, though a brief strengthening of the trade winds tomorrow could lead to a small bump in surf.

HFO WATCHES/WARNINGS/ADVISORIES

None.