261 FXHW60 PHFO 250135 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 335 PM HST Wed Sep 24 2025 .SYNOPSIS... A cold front will move over Kauai overnight bringing widespread showers and a slight chance of thunderstorms Thursday into Friday. Weakening trades will allow land and sea breezes over the rest of the state to bring afternoon interior showers. Additional showers and thunderstorms may trigger on the Big Island Friday and Saturday afternoons. Trades and more stable weather move in Sunday. && .DISCUSSION... Trade winds are weakening across Hawaii this afternoon in response to a low pressure system approaching from the northeast. The associated cold front is moving quickly southwest towards our area, and should reach the western end of the state after midnight tonight, and expect an increase in clouds and showers as the low level moisture moves in. A low aloft is positioned near 30N150W that will also track southwest and bring in colder air aloft that will destabilize the atmosphere across the western end of the state Thursday into Friday. The moisture and instability maximizes just north of Kauai and will bring the potential for some heavier showers and a slight chance of thunderstorms. The front will weaken to a trough as it gets wound up by a developing surface low along the front. Winds will shift southerly as this feature sets up, but speeds will be light allowing localized sea breezes by Thursday afternoon that will focus clouds and shower over interiors of all islands. Widespread showers should surround Kauai through the day into Thursday night with Oahu along the southern edge of the shower band. Shower coverage will become a bit more diffuse Friday into Saturday across the smaller islands, but could fire up again along island interiors in the afternoons. Meanwhile, the southerly flow will bring deeper tropical moisture over the Big Island, potentially triggering showers and thunderstorms Friday and Saturday afternoons. The low pressure system north of the island chain will begin to drift westward away from the Hawaiian Islands from Sunday into Monday. This change in the weather pattern will allow the broad ridge north of the region to build in allowing more stable trade wind weather to return to the islands by next week Tuesday and Wednesday. Expect moderate to locally breezy trade winds along with brief passing showers during this time period, favoring the windward mountain areas in the overnight to early morning hours. && .AVIATION... Trade winds will diminish into light and variable land and sea breezes tonight as a weak frontal boundary nears Kauai overnight. The front will stall and weaken to a trough generating clouds and showers near the island of Kauai Thursday and Friday. Showers may be heavy at times with periods of MVFR conditions. Isolated thunderstorms are possible. No AIRMETs are currently in effect. && .MARINE... Trade winds will weaken today in response to a low pressure system to the north with an associated cold front stretching into the northern offshore waters. The front and low will move south, and the front is expected to weaken into a trough and could stall in between Kauai and Oahu tomorrow afternoon. Winds will become light and southerly tonight into tomorrow with the exception of the northwestern waters of Kauai where northeasterly winds are still expected until Friday. By Friday and Saturday, light southerly winds are expected statewide before trade winds build back in by Sunday in response to a high pressure ridge moving in. Trade winds can then be expected early next week. A close proximity low pressure system to the north with northerly winds pointed towards the islands will send a moderate medium period N-NNE swell to N facing shores tonight and peak tomorrow afternoon. There is also a small NW swell that will be filling in tomorrow through the weekend helping to keep surf heights slightly elevated. A small medium period NW swell is then expected to fill in Monday and decline slowly through next week. Tiny to small background N and NW pules will keep north shores from going completely flat for the remainder of next week. Surf for south facing shores will remain small through tomorrow before a small long period south swell arrives on Friday and peaks over the weekend at or slightly above the September average (5 ft). Surf for east facing shores will stay small today then will likely see an increase from the N-NNE swell tomorrow and Friday. The islands to see the greatest increase would be Kauai and Oahu, as these islands are most directly within the fetch area of the low to the north. This swell will fade out by the weekend. Trade wind chop could increase by Sunday as trade winds return. && .FIRE WEATHER... Forecast trend towards both weakening winds and higher humidity across the state through the weekend. Critical fire thresholds are not expected over the next several days. Moderate trade winds and drier conditions expected by next week. Weak, elevated inversion around 7-9 kft today should erode and disappear Thurs Temperature inversion heights near Maui and the Big Island today will range from 6,000 to 7,000 feet elevation. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION/FIRE WEATHER...Foster AVIATION...Almanza MARINE...Tsamous