Marine Weather and Tide Forecast for Urban Honolulu, HI

SHORT TERM UPDATE

Minor updates were made to PoPs to account for recent trends.
Otherwise previous forecast is on track.

PREV DISCUSSION
Issued at 301 PM HST Thu Oct 15 2026

Radar showed scattered windward and mauka showers over each island this afternoon, with additional Kona showers developing. Northeast trade winds were a little stronger than yesterday, averaging 10 to 20 mph with gusts 20 to 30 mph fairly common.

A large surface high continues to strengthen to our north. Aloft, a weak upper level low to our east will become a trough that stretches from southern CA all the way out to us. The trough will be weak, and apart from a slight increase in instability, we won't see much from it.

Several impulses of increased moisture will move west toward and over the state, especially the eastern end, over the coming week.
The first will move through Friday afternoon and evening, and reach all islands. We have continued the trend of the previous shift and further increased the chance of rain through this window of time. The second should move over the area late Sunday through late Monday, boosting showers mainly across the eastern end of the state. Again, PoPs have been further increased. Finally, another area may reach us next Thursday, but at this time range confidence is low. Models currently indicate the focus of this one would be on the eastern end.

Trade winds will remain moderate to breezy through the coming week, with the a slight increase possible Tuesday evening. A slight weakening may develop next Thursday, but as mentioned in the previous paragraph, at seven days out, confidence in that level of detail is low.

Finally, both the latest GFS and ECMWF indicate that the upper level trough extending from southern CA over to us may join with energy moving in from the northwest and strengthen toward the middle of next week. It is unclear at this time whether it will develop into a closed low or a stronger trough. Either way, it may draw tropical moisture northward toward the state and present a heavy rain threat. Details should become clearer in a few days.

AVIATION

A high pressure system far north of the Hawaiian Islands will drift slowly eastward over the next few days, increasing easterly trade wind speeds. An easterly wave riding into the islands on the easterly trade winds will bring increasing showers spreading from east to west across the islands from Friday afternoon near the Big Island into Saturday across the state. Periods of MVFR conditions and showers will develop over windward mountain areas.

AIRMET Sierra remains in effect for tempo mountain obscuration abv 020 for north and east sections of the Big Island.

AIRMET Tango is in effect for moderate low level turbulence downwind of island terrain.



MARINE
Issued at 301 PM HST Thu Oct 15 2026

Surface high pressure far north of the islands will build as it shifts northeast of Hawaii through Saturday. As a result, trade winds will gradually increase to fresh to locally strong levels over the next couple of days. A Small Craft Advisory (SCA) is in effect for the typically windy waters around Big Island and Maui through Saturday and may need to be expanded in area as the high builds to the north. Elevated trade winds will persist into early next week.

The current small bump in the northwest swell will fade tonight before a moderate north-northwest swell arrives Friday. Surf along north and west-facing shores should top out near or slightly above seasonal average during the peak of the swell Friday afternoon and Saturday, then slowly decline late Saturday and Sunday as the dropping swell shifts more northerly and a smaller overlapping northwest swell arrives. Both swells will fade early next week.

A new long-periond south swell will gradually build this evening and may push surf along south-facing shores back above seasonal average into Friday. This swell will slowly decline Saturday through early next week.

Surf along east-facing shores will gradually increase tonight into Friday as trade winds strengthen over the region. Expect some wrap from the moderate north-northwest swell Friday afternoon into Saturday. This swell along with developing rough trade wind swell will produce east shore surf above seasonal average Saturday

FIRE WEATHER
Issued at 301 PM HST Thu Oct 15 2026

Surface high pressure north of the islands will produce moderate to breezy trade winds for the next few days. Minimum relative humidity levels will for most areas remain out of critical fire threshold ranges. The stronger trade winds will mainly impact higher elevation areas with even higher minimum humidity levels.
Subsidence temperature inversion heights today near Maui and the Big Island should range from 9,000 to 11,000 foot through Friday.

HFO WATCHES/WARNINGS/ADVISORIES
Small Craft Advisory until 6 PM HST Saturday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.