Marine Weather and Tide Forecast for Hilo, HI

SHORT TERM UPDATE

A well-developed and weakly convergent band of shower bearing cu is advancing toward Windward Maui and the Hamakua Coast of the Big Island at press time this morning. Given orientation perpendicular to the island chain and appearance on visible satellite, suspect a few inches of rain will be possible for select windward locales tonight. Primary concern is potential for this feature to shear apart as it encounters acceleration of the boundary layer flow upon approaching the Alenuihaha Channel between the Big Island and Maui. For that reason, and because guidance demonstrates questionable handling of this feature, will leave official forecast untouched pending further observational evidence this afternoon. Regardless, some degree of enahnced showers can be expected from Windward Kauai through the Hamakua Coast tonight.

PREV DISCUSSION
Issued at 357 AM HST Wed Jul 8 2026

Current radar and satellite imagery shows scattered showers moving into windward and mauka areas on the trade wind flow this morning. Strong high pressure centered far north of the state will continue to drive breezy to windy trades across the region through the weekend. Looking aloft, Hawaii will remain under weak ridging through early next week as it lies between two upper- level lows, one to the east, the other to the west.

The breezy to windy trades will generally focus clouds and showers over windward and mauka areas throughout the period.
However, batches of deep tropical moisture will move across the area tonight through Friday night, again Sunday into Monday, and more will follow next week. As these batches of deeper moisture move through with PWATs reaching 1.5 to 2 inches, the inversion will weaken and lift, increasing shower coverage and frequency across the state. In addition to the potential for an uptick in shower activity, dew points will be on the rise, leading to muggier conditions through the weekend.

AVIATION
Breezy to locally strong trades will continue today and once again bring low clouds and scattered showers predominately to windward and mountain areas. There will also be isolated spillover into leeward sites. VFR will prevail for most sites, with occasional localized MVFR mainly for windward/mountain sites associated with the shower activity.

AIRMET Tango remains in effect for moderate low level turbulence over and downwind of terrain for all islands. This AIRMET will likely continue through the next several days.



MARINE
Issued at 357 AM HST Wed Jul 8 2026

Strong high pressure remains centered north of the state, which is driving fresh to strong trade winds across all coastal waters.
No ASCAT pass available overnight, but hi-resolution guidance keeps Small Craft Advisory (SCA) winds in many of the coastal water zones though tonight, so will be extending the current SCA through then. Very little chance is expected to the strength of the high or the pressure gradient across the islands, so will continue to remain around the advisory threshold for most waters over the coming days. Windy zones around Big Island and Maui County will likely be extended beyond tonight at a minimum for the SCA, with the possibility of more zones.

A moderate, medium period south southwest (190-200 degrees) swell continues to generate moderate surf below advisory criteria along south facing shores. This swell energy will gradually lower through the remainder of the week. Expect small surf for south facing shores leading into this weekend, with mainly background energy. Another moderate, long-period south southwest swell (210 degrees) is expected to fill in Saturday night, but due to the direction of the source, could be more inconsistent than the current swell.

Surf along east facing shores will remain rough and choppy through the week as fresh to strong trades hold. A small, moderate period west (280 degrees) swell is expected to arrive this weekend and linger into early next week. No significant swells are expected out of the north or northwest.

Looking ahead, higher than normal high tides will be possible beginning during the second half of this weekend. Interests immediately along the coasts in low-lying or vulnerable areas should continue to monitor forecasts for possible coastal flooding due to the King Tides from Sunday through the first half of next week.

HFO WATCHES/WARNINGS/ADVISORIES
Small Craft Advisory until 6 AM HST Thursday for Alenuihaha Channel-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- Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.