West Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Lows 70 to 75 near the shore to around 61 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny. Highs 86 to 93 near the shore to around 79 above 3000 feet. East winds up to 15 mph.

Monday Night: Mostly clear. Lows 71 to 76 near the shore to around 62 above 3000 feet. East winds around 10 mph.

South Kaua’i

Tonight: Partly cloudy with scattered showers. Lows around 74. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 84 to 91. East winds 10 to 15 mph. Chance of rain 30 percent.

Monday Night: Partly cloudy with isolated showers. Lows around 74. East winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 64 to 70 in the valleys to around 59 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 86 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy with scattered showers. Lows 65 to 71 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 65 to 74. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny. Isolated showers in the morning. Highs 79 to 89. East winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Mostly clear with isolated showers. Lows 66 to 75. East winds around 10 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 65 to 78. East winds up to 10 mph. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers. Highs 76 to 89. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Partly cloudy with isolated showers. Lows 65 to 78. East winds around 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Stable, mostly dry conditions will continue into the first half of the work week. Trade winds will veer slightly east southeasterly and weaken a bit into the moderate range. Trade wind showers will be few and far between. The one exception will be the Big Island, which could see increased showers over the Kona slopes through mid-week. More typical easterly trades look to return during the second half of this week.

Discussion

This afternoon, very dry conditions are prevailing across the main Hawaiian Islands. Ridging both at the surface and aloft northeast of the island chain is the main influence of weather across the region, maintaining persistent warm, stable, and dry conditions. Latest satellite imagery shows most areas are cloud and shower-free this afternoon, with the exception of daytime sea-breeze induced cloud buildups along the Kona slopes of the Big Island. There are also a few clouds over interior Kauai, which is located closer to a trough passing north of the state. Surface observations and an ASCAT pass show that wind speeds are generally in the moderate range with some locally breezy gusts.
Little change is expected over the next few days. A low pressure system will push eastward across the north Pacific through Wednesday. As this occurs, a trough will allow the pressure gradient over the island chain to relax slightly. Wind speeds across the islands will follow suit, easing slightly when compared to those observed today, and veering east southeast. The lighter winds will also be conducive to sea-breeze development across terrain-sheltered areas. Model guidance continues to show a minor increase in moisture approaching from the southeast and passing across Big Island late Monday through Tuesday night. This moisture may enhance afternoon showers over the Kona slopes through mid-week. However, very dry air aloft across the remainder of state will remain firmly in place. Therefore, other than localized afternoon breeze activity, very few showers are expected, aside from brief terrain-enhanced windward upslope mauka showers.
A new high far north-northeast of the state will become established during the second half of the week, allowing more typical easterly trade winds to return.

Aviation

Stable, moderate to breezy trades will continue to deliver clouds and showers to windward and mountain areas through the period, particularly overnight and during the early morning hours. Isolated MVFR will be possible within showers. Otherwise, VFR will prevail.
No AIRMETs are in effect and none are anticipated to be needed through tomorrow.

Marine

High pressure north of the Hawaiian Islands maintains moderate to fresh trades through the week. Small swell energy emanating from the southerly quadrant slowly declines into Monday. A series of small longer period S swells then arrive by Tuesday providing a modest boost to S shore surf through Friday. Surf along N and W facing shores remains nearly flat while surf along E shores will remain characterized by short period chop.

Fire weather

Elevated fire weather conditions will continue for the next couple of days due to the low relative humidity values. Very dry conditions were observed across the state today, with RH dropping into the 30s and 40s this afternoon. This is expected to be the case again through Tuesday with dry air remaining in place. Despite these dry conditions, however, marginal wind speeds have kept the need for Fire Weather headlines at bay. With the winds expected to ease further Monday through Tuesday, not anticipating the need for any fire weather headlines at this time.

HFO Watches/Warnings/Advisories

None.

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