Forecast Discussion

Synopsis

14 Jul 2025 01:14:00 GMT: Moderate to locally breezy trade winds will persist for the next several days with slight variations. Typical summertime scattered clouds and showers will mainly focus along windward and mauka areas. An increase in shower activity is expected Monday afternoon into Tuesday.

Discussion

14 Jul 2025 01:14:00 GMT: A surface high far northeast of the islands will maintain moderate to locally breezy trade winds across the island chain through at least Monday. A mid-upper level low currently sits around 500 miles north of Kauai with ridging aloft elsewhere, resulting in a strong inversion around 5800 feet on the morning Hilo sounding and a higher and weaker one for the western end of the island chain (Lihue). Despite the slight instability near Kauai, a pocket of drier air is moving through the state today, providing a brief break from the increased low clouds and showers of the past few days. This is reflected in the isolated to scattered stable cumulus and minimal showers moving into windward areas and over leeward slopes of the Big Island on today's visible satellite and radar imagery. Expect an increase in showers Monday afternoon into Tuesday as an area of higher moisture moved through the state. Shower activity will increase for windward Big Island Monday afternoon, spread into the central islands Monday night, then reach Oahu and Kauai by early Tuesday morning. As an upper level low, currently positioned several hundred miles north of the state, retreats off to the north beginning late Monday, mid to upper level ridging will fill in over Hawaii. This will set the stage for several days of typically drier and stable summer weather, with moderate to breezy trade winds and shower activity subdued. A modest bump in trade wind speeds is possible during the second half of the week as the high far to the northeast strengthens slightly and drifts closer to the islands.

Aviation

14 Jul 2025 01:14:00 GMT: High pressure far north-northeast of the islands will maintain moderate trades. Some clouds and showers riding in on the trade wind flow will favor the windward and mauka areas of the islands, but overall rainfall amounts are expected to be light. Overall VFR conditions are expected to prevail, however some pockets of MVFR conditions are possible mainly during the overnight hours. No AIRMETs are in effect, and none are expected through Monday.

Marine

14 Jul 2025 01:14:00 GMT: A ridge of high pressure will remain far north of the state throughout the week. Currently, a weak trough to the northwest of the state has relaxed the pressure gradient some and is causing the trade winds to be at speeds just below Small Craft Advisory (SCA) levels. Moderate to fresh trades will likely continue through Monday then strengthen to locally strong speeds from Tuesday onward as the trough exits the region. SCA should return to our typically windy waters around Maui County and the Big Island by Tuesday evening. Surf along south facing shores should see a modest increase over the next few days due to a pair of south and south-southeast swells. A long-period south swell should fill in on Monday and peak on Tuesday near the summer average. As the long-period south swell begins to decline, there should be some reinforcing energy from the south-southeast Tuesday or Wednesday, which should help maintain surf heights through the middle of the week. Surf should gradually decline Thursday into Friday, but another modest increase is expected late Friday into the weekend as a new long- period southwest swell arrives from the Tasman Sea. Surf along east facing shores will continue to remain choppy with surf heights below average due to the lack of strong trades locally and upstream of the state. A sight increase is expected towards the middle of the week as the trades strengthen a notch. A tiny northwest swell could produce some rideable surf along north facing shores Monday into Tuesday.

Fire weather

14 Jul 2025 01:14:00 GMT: Trade winds will remain moderate to locally breezy for the next several days. Aside from a period of higher humidity and an increase in shower activity later Monday into Tuesday, the atmosphere will remain rather dry for much of the coming week with typical summer fire weather conditions.