West Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to around 56 above 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 81 near the shore to around 69 above 3000 feet. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 50 percent.

Tuesday Night: Partly cloudy. Isolated showers in the evening. Lows around 67 near the shore to around 58 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows around 66. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 76 to 82. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tuesday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 67. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows 58 to 65 in the valleys to around 54 above 4000 feet. Light winds. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 72 to 78 in the valleys to around 63 above 4000 feet. Light winds. Chance of rain 50 percent.

Tuesday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 60 to 66 in the valleys to around 56 above 4000 feet. Light winds becoming south up to 10 mph after midnight. Chance of rain 40 percent.

North Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 60 to 67. South winds up to 10 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 72 to 80. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows 61 to 69. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 61 to 70. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 70 to 81. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 62 to 71. Light winds. Chance of rain 40 percent.

Detailed Forecast

Synopsis

A significant pattern change is then expected by Tuesday as an upper level trough and surface low pressure evolve northwest of the islands. This system is expected to draw deep tropical moisture northward over the state, leading to an extended period of strong southerly winds, increased chances for widespread rainfall and thunderstorms, and renewed flooding concerns from from the middle of the week through this weekend.

Short term update

Issued at 901 PM HST Mon Apr 6 2026
The latest forecast remains on track, so no amendments will be required with this update. Light to moderate trades across predominately windward portions of the state and land-sea breezes holding present across leeward portions, namely along the Kona coastline of Big Island. Shower activity is slowly deteriorating across the Hawaiian Islands; the calm before the storm, so to speak. Guidance continues to depict an upper-level trough and associated surface low to evolve northwest of the islands Tuesday, the catalyst to an increase of moisture across much of the state.

Prev discussion

Water vapor imagery shows an approaching upper level trough over the Northwest Hawaiian Islands this afternoon. Occasional cirrus clouds along the eastern flank of the trough will continue over the next day or so. At the surface, a ridge is northeast of the state with the axis passing through 30N140W. To the northwest, a cold front around 575 miles northwest of Kauai tracking east at 10 mph. Gentle to moderate southeast winds prevail with lighter winds/land breezes setting up leeward due to the Big Island wind blockage. Most islands will see decreasing showers and clearing tonight except for Kauai where clouds and showers will begin to enhance due to the upper trough.
A broad surface trough is expected to develop ahead of the front, just northwest of the islands early on Tuesday, reinforcing and strengthening south winds across the islands. A moisture band associated with the trough will also set up around Kauai on Tuesday around the time the upper trough moves across this area bringing a chance for heavy showers. Deep tropical moisture will be drawn northward in the south flow. The combination of daytime heating, sea breezes, and a potent shortwave trough moving through, may even trigger some heavy showers or thunderstorms over interior areas on Tuesday. 0-6 km bulk shear values in excess of 60 knots may allow some of these thunderstorms to become organized and produce brief strong gusts on Tuesday, before dropping off Tuesday night. The upper trough exits Tuesday night while the deep tropical moisture builds northward, but the brief returning stability may be enough to provide a period of less-intense showers Tuesday night into Wednesday morning.
Upper-level forcing is forecast to strengthen again Wednesday as a strong second shortwave rounds the base of the trough, potentially enhancing lift over the region while surface low pressure center organizes west of the islands. The combination of deep tropical moisture engulfing the state, increasing large- scale forcing for ascent point towards another widespread and organized rainfall event for the state. Therefore, a Flood Watch has been issued for all islands from Wednesday morning through the day Friday.
South winds will ramp up likely to advisory levels Wednesday night through Friday morning. Strong winds will occur in and around heavy showers and thunderstorms, as well as around mountain ridges and downsloping gusts over northern and windward slopes of all islands. Severe wind gusts (58 mph+) will be possible, though most areas will see max in the 40-50 mph range, and likely more of a Wind Advisory setup. Stay tuned for more information on that. Finally, a Winter Storm Watch has been posted for a combination of freezing rain and snow on the Big Island summits above 12,500 feet also running Wednesday through Friday.
Differences remain in the global models for the weekend, but the general consensus is that the active pattern could linger in the area. The ECMWF clears out much of the state of the bulk of the rain, but the GFS continues the potential for rain across at least portions of the state through the weekend and beyond, where the deep moisture axis anchors.
As previous discussions have mentioned, one important consideration with this week's rainfall is antecedent conditions. The islands experienced significant flash flood events in recent weeks, and despite several days of drier trade wind weather, soils remain vulnerable in many areas. As a result, any time period of higher rainfall rates could quickly lead to enhanced runoff, renewed rises in streams and reservoirs, and localized flash flooding concerns.

Aviation

Trades will continue to weaken heading into the evening as an upper-level disturbance moves in and initiates a wet week across the islands. VFR conditions are expected to prevail through at least sunrise tomorrow, however rain may start to move in for Kauai and even Hilo by late morning Tuesday. Rain is then expected to slowly spread across the islands afterward.
AIRMET Tango remains in effect for upper level turbulence between FL300 and FL350 over the islands and is expected to continue through the period. AIRMET Sierra was dropped for windward Oahu, but another may be issued for other islands as this aforementioned disturbance moves in with more moisture.

Marine

Moderate to locally fresh trades will gradually ease and shift southeasterly tonight through Wednesday as a front stalls just west of the islands and high pressure far north of the islands moves slowly eastward. The winds will turn more southerly and increase to moderate and strong levels on Thursday as a low pressure system develops along the stalled frontal boundary.
Small northwest swells will keep some small surf along north facing shores through this evening. A moderate long-period northwest swell will fill in tonight and Tuesday, giving more of a boost to north shore surf late Tuesday through Wednesday. A small, short- period north-northeast swell will fill in during the day Tuesday before peaking Wednesday and subsiding Thursday. This overlap will make for some rough choppy conditions along north facing shores.
A small southerly swell will keep some small surf in place along south facing shores through this evening. A slightly larger, long- period south swell, will fill in tonight, giving a more noticeable increase to south shore surf Tuesday. Surf could reach advisory levels by Wednesday before slowly easing Thursday into the weekend. Strengthening southerly winds will make for rough and choppy surf by late next week.
East shore surf will remain small and below the seasonal average due to a lack of strong trade winds over and upstream of the islands, except for some wrap from the northerly swells.

HFO Watches/Warnings/Advisories

Flood Watch from Wednesday morning through Friday afternoon for Big Island East, Big Island Interior, Big Island North, Big Island South, Big Island Southeast, Big Island Summits, Central Oahu, East Honolulu, Ewa Plain, Haleakala Summit, Honolulu Metro, Kahoolawe, Kauai East, Kauai Mountains, Kauai North, Kauai South, Kauai Southwest, Kipahulu, Kohala, Kona, Koolau Leeward, Koolau Windward, Lanai Leeward, Lanai Mauka, Lanai South, Lanai Windward, Maui Central Valley North, Maui Central Valley South, Maui Leeward West, Maui Windward West, Molokai Leeward South, Molokai North, Molokai Southeast, Molokai West, Molokai Windward, Niihau, Oahu North Shore, Olomana, South Haleakala, South Maui/Upcountry, Waianae Coast, Waianae Mountains, Windward Haleakala.
Winter Storm Watch from Wednesday morning through Friday afternoon for Big Island Summits.

Data Courtesy of NOAA.gov