textproduct: Honolulu

SYNOPSIS

An upper-level low northeast of the islands will remain nearly stationary through Friday, enhancing clouds and showers with moderate to locally breezy trade winds prevailing. This weekend, the upper low is forecast to move northeast away from the state, and wind speeds will decrease slightly. Mainly windward and mauka showers are expected, with limited spillover into leeward areas. Moderate trades will prevail into early next week, followed by lighter flow a land/sea breeze pattern thereafter.

DISCUSSION

Issued at 835 PM HST Thu Apr 30 2026

Moderate to breezy trade winds are forecast to continue for the next several days thanks to a series of high pressure systems that will move from west to east across the North Pacific. An upper- level low centered 600-700 miles northeast of the state is causing some local instability resulting in deeper clouds and some enhanced shower activity across windward and mauka areas, with isolated showers reaching leeward areas. This upper-level low will remain nearly stationary through Friday, keeping some cold air aloft over the region. This will continue the risk of occasional moderate to briefly heavy showers.

Trade wind speeds should weaken slightly Saturday into Sunday as the upper-level low exits the region to the northeast. Periods of showers will continue to favor windward and mauka areas. Moderate trades will continue into early next week, though a weakness in the ridge could reduce speeds further as early as Tuesday. This scenario would support daytime sea breezes and nighttime land breezes beginning as early as Tuesday and lasting through the middle of the week.

AVIATION

Issued at 315 PM HST Thu Apr 30 2026

A stationary upper low is situated northeast of Hawaii that will enhance some of the incoming low clouds and showers that will focus windward by fresh trade winds. Will be monitoring for mountain obscurations due to showers over windward slopes tonight, but coverage is brief/isolated for now.

AIRMET Tango is posted for tempo moderate turbulence across leeward sides of all islands below 8000 feet due to the breezy trade winds. Expect this AIRMET to continue into Friday.

MARINE

Issued at 835 PM HST Thu Apr 30 2026

Fresh to strong easterly trades are expected to strengthen overnight into Friday as high pressure builds north-northeast of the state. As a result, the Small Craft Advisory has been expanded to include all Hawaiian waters. Winds will gradually ease over the weekend as the ridge weakens in response to a front passing far north of the islands. This downward trend should allow winds to fall below advisory levels across most, if not all, waters by the end of the weekend, with similar conditions lingering into Monday. Trades are then forecast to ease further Tuesday through midweek, potentially allowing a land and sea breeze pattern to develop near the coasts.

Surf along exposed north and west-facing shores will build above early May averages this weekend due to a relatively active northern Pacific pattern for this time of year. Although offshore buoys have yet to detect this new swell energy, long-period northwest (320 deg) forerunners are expected to arrive by daybreak Friday, leading to a gradual increase through the day. Surf heights could approach advisory levels Friday night into Saturday, particularly if the swell arrives larger than currently forecast. This swell will then gradually ease through the weekend. Another, slightly smaller northwest pulse is expected early next week, maintaining elevated surf along north and west-facing shores. Looking ahead, guidance indicates yet another long-period northwest (320 deg) swell may arrive late next week, generated by a developing storm near Japan that is forecast to lift northeast toward the Kuril Islands over the weekend.

Surf along south-facing shores will trend up over the weekend as a long-period south-southwest pulse arrives. Expect a peak later in the weekend and into Monday before lowering.

Surf along east-facing shores will briefly rise (rough/short- period surf) through the day Friday in response to the strong trades locally and upstream. A downward trend is then anticipated as the trades ease over the weekend.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 PM HST Friday for all Hawaiian waters-