West Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 71 to 76 near the shore to around 64 above 3000 feet. East winds up to 15 mph in the evening becoming light. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs 85 to 91 near the shore to around 78 above 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Wednesday Night: Mostly clear. Haze after midnight. Lows 70 to 76 near the shore to around 63 above 3000 feet. East winds around 10 mph.

South Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 72 to 77. East winds 10 to 20 mph. Chance of rain 40 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 81 to 89. East winds around 10 mph. Chance of rain 40 percent.

Wednesday Night: Partly cloudy with isolated showers. Haze after midnight. Lows 72 to 77. East winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows 67 to 72 in the valleys to around 60 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Highs 75 to 84 in the valleys to around 67 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday Night: Partly cloudy with isolated showers. Haze after midnight. Lows 66 to 72 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

North Kaua’i

Tonight: Partly cloudy with scattered showers. Lows 67 to 75. East winds up to 15 mph. Chance of rain 40 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 88. East winds up to 10 mph. Chance of rain 40 percent.

Wednesday Night: Partly cloudy with isolated showers. Haze after midnight. Lows 66 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 66 to 78. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 87. East winds around 10 mph. Chance of rain 50 percent.

Wednesday Night: Partly cloudy with isolated showers. Haze after midnight. Lows 66 to 78. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will prevail through the week, with showers favoring windward and mauka areas. Aside from scattered afternoon showers on the South Kona slopes of the Big Island, leeward areas will be mostly dry. Winds will begin to weaken later this week leading to more widespread leeward sea breezes and bringing higher chances for interior and leeward showers, mainly across the western islands.

Discussion

A broad surface high well north of the Hawaiian Islands continues to drive moderate to locally breezy easterly trades. Meanwhile, upper-level ridging has settled over the islands resulting in increasingly dry and stable conditions. This has resulted in a decrease in shower activity across the state, with isolated windward and mauka showers this afternoon. Aside from a few showers over the South Kona slopes of the Big Island, leeward areas remain dry.
However, subtle changes are looming in the near future, as a strengthening upper-level trough and associated surface trough propagate just northwest of the islands. This will lead to a shortwave passing in the vicinity of Kauai, resulting in the development of sea breezes in the afternoon for western slopes of island mountains and increased shower activity for leeward areas, despite the overall drier conditions still in place.
Latest model guidance still supports a return of stable summertime trades during the latter half of the week as the aforementioned troughs to the northwest weaken. Trades will be slightly lighter in strength initially, but are progged to increase back to moderate to locally breezy by the end of the forecast period, as well as more typical shower activity to windward and mauka areas.

Aviation

Moderate to locally breezy trades will persist through tomorrow. Expect low clouds and showers to favor windward and mountain areas, where MVFR conditions will be possible, particularly overnight. In addition, with low level winds veering slightly out of the ESE, isolated sea breezes may increase cloud cover over some leeward areas tomorrow afternoon. Otherwise, VFR conditions are expected to prevail.
No AIRMETs are currently in effect.

Marine

Moderate to locally strong easterly trade winds will continue through Friday as surface high pressure remains centered far north of the Hawaiian Islands. A Small Craft Advisory remains in effect for the waters around Maui County and the windier waters around the Big Island. Lighter winds are forecast from Friday night into the weekend.
A long period southwest swell will slightly boost surf heights along south and some west facing shores late tonight through the weekend. Surf along east facing shores will remain small and choppy through the forecast period. Surf along north facing shores will remain nearly flat through the forecast period.
Peak monthly high tides associated with the lunar cycle, combined with water levels that are running higher than predicted may lead to minor flooding along the shoreline and in low-lying coastal areas. Coastal flooding is expected around the daily peak tide each afternoon through Thursday. A Coastal Flood Statement has been issued for Maui County and the Big Island.

Fire weather

Locally breezy, dry, and stable conditions will continue through the week. With near critical relative humidity possible the next couple of days expect elevated fire weather concerns, especially over drier leeward areas. Winds are expected to weaken later this week.
The current KDBI value at the Honolulu International Airport has exceeded the 600 threshold, currently 604, and will remain above this threshold until significant rain occurs, which is unlikely for weeks or possibly months as the peak of the dry season is near.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Wednesday for Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.