Hilo

Tonight: Partly cloudy with isolated showers. Lows 66 to 72 near the shore to around 59 at 4000 feet. East winds up to 10 mph shifting to the southwest after midnight. Chance of rain 20 percent.

Juneteenth: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 85 near the shore to around 72 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Friday Night: Mostly cloudy with scattered showers. Lows 66 to 72 near the shore to around 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy. Scattered showers in the evening. Lows 67 to 75 near the shore to around 56 near 5000 feet. Light winds. Chance of rain 40 percent.

Juneteenth: Sunny. Isolated showers in the afternoon. Highs around 88 near the shore to around 71 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday Night: Mostly clear. Isolated showers in the evening. Lows 68 to 76 near the shore to around 57 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 74 near the shore to 61 to 68 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Juneteenth: Mostly sunny with isolated showers. Highs around 83 near the shore to 71 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 74 near the shore to 61 to 68 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kohala

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 74 near the shore to 61 to 68 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Juneteenth: Mostly sunny with isolated showers. Highs around 83 near the shore to 71 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 74 near the shore to 61 to 68 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly clear. Breezy. Lows around 76 near the shore to around 58 near 5000 feet. Northeast winds up to 20 mph.

Juneteenth: Sunny and breezy. Highs around 88 near the shore to around 71 near 5000 feet. East winds up to 20 mph.

Friday Night: Mostly clear. Lows around 76 near the shore to around 58 near 5000 feet. East winds around 10 mph.

Puna

Tonight: Partly cloudy with isolated showers. Lows 66 to 72 near the shore to around 59 at 4000 feet. East winds up to 10 mph shifting to the southwest after midnight. Chance of rain 20 percent.

Juneteenth: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 85 near the shore to around 72 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Friday Night: Mostly cloudy with scattered showers. Lows 66 to 72 near the shore to around 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Partly cloudy with isolated showers in the evening, then clear after midnight. Lows 70 to 76 near the shore to 55 to 60 above 4000 feet. Light winds. Chance of rain 20 percent.

Juneteenth: Sunny. Isolated showers in the afternoon. Highs 85 to 90 near the shore to 66 to 75 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Mostly clear. Lows 71 to 76 near the shore to 55 to 60 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

A weak surface trough and its associated moisture plume over the western end of the state will shift northwest through Friday, bringing a slight uptick in shower activity as it passes through. Otherwise, a lighter background flow will allow for a sea/land breeze pattern to persist into the weekend with showers developing over leeward and interior areas each afternoon, followed by clearing at night. Then trade winds will gradually strengthen through next week, shifting the shower focus to windward and mauka areas.

Short term update

A weak surface trough, currently located west of Oahu, edged slowly northwestward today. Light flow allowed for diurnal coastal sea breezes to form in the early afternoon. Moderate to heavy showers developed along the Koolau range on Oahu over north Kauai with the help of ample low level moisture and weak instability from the trough. Southerly winds were noted in the 00Z Lihue sounding from 2500 ft to around 12000 feet. This helped push shower activity that formed over the interior of the islands and mountains, northward. Flood Advisories were needed for both central portions of windward Oahu and far northern Kauai. Though shower intensity on RADAR has been trending downward this evening, showers may still continue close the trough tonight, mainly over Kauai and Oahu. In the update, rainfall chances were upped slightly along windward Oahu and north Kauai as left over weak boundaries, amble low level moisture, and marginal instability exist. The rest of forecast appeared on track.

Prev discussion

Issued at 311 PM HST Thu Jun 18 2026 Radar and visible satellite imagery show a slightly veered east- southeast flow steering clouds and isolated showers parallel to the island chain this afternoon. The bulk of the clouds and showers are remaining just east of the state and along a weakly convergent boundary associated with the weak surface trough near Kauai, but clouds and a few showers have also managed to develop over leeward and interior areas of each island with the afternoon sea breezes.
The surface trough will weaken further and gradually shift northwest of the state through Friday, with moderate east- southeast winds filling in behind it through Saturday. Winds will briefly take on an east-northeasterly tilt on Sunday as a front/trough approaches from the northwest. With wind speeds gradually strengthening, a mix of windward and mauka showers with isolated afternoon sea breeze leeward and interior showers can be expected through the weekend. In addition, dew points are expected to remain in the 70s for many locations through Saturday, maintaining muggy conditions through much of the weekend.
Heading into next week, the subtropical high to the far northeast will regain control and easterly trades will build to moderate to breezy levels through midweek. This will usher in slightly lower dew points, and combined with the breezier trades, some relief from the mugginess. Model guidance suggests that an upper level low will pinch off of the longwave trough to the far north and approach the state from the northeast mid to late-week, possibly providing some enhancement to windward and mauka showers as batches of moisture move through.

Aviation

A departing surface trough continues to make for windward showers across Kauai and Oahu this evening. A weakened trade wind pattern remains in place, leading to land/sea breezes across most sites, however a return to steady trades over the next several days is expected. VFR conditions are broadly expected to prevail, however windward sites may see periods of MVFR under occasional shower activity.
AIRMET Sierra remains in effect for Kauai through Maui County due to mountain obscuration from showers. Conditions are improving for Maui County as of this TAF issuance, but mtn obsc may linger longer for Kauai and Oahu as this system remains within the vicinity of the islands.

Marine

Issued at 311 PM HST Thu Jun 18 2026 Light to moderate trades will hold for the next few days as a weak surface ridge remains to the north and a broad surface trough continues to move west over the island chain the next few days. The weak trough is currently located between Oahu and Kauai waters and is producing some scattered showers over the coastal and offshore waters. Scattered showers will generally decrease over the coastal waters by Friday. Trades may increase slightly over the weekend as the trough dissipates, with more pronounced strengthening early next week as the ridge strengthens to the north.
A moderate, long period south swell is peaking at advisory levels this afternoon, thus a High Surf Advisory remains in effect for all south facing shores through early Friday morning. This swell should drop below advisory levels by Friday as the swell gradually fades late tonight into the weekend. A series of smaller south- southwest swells will fill in Sunday into the first half of next week and will maintain surf near seasonal averages through next week.
Tiny surf will prevail on north and east shores through most of the coming week. A slight increase in east shore surf is expected around next Tuesday or Wednesday as trade winds build across the region.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Friday for Big Island South, Big Island Southeast, East Honolulu, Ewa Plain, Honolulu Metro, Kahoolawe, Kauai South, Kauai Southwest, Kona, Lanai Leeward, Lanai South, Maui Central Valley South, Maui Leeward West, Molokai Leeward South, Niihau, South Haleakala, South Maui/Upcountry, Waianae Coast.

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Data Courtesy of NOAA.gov