Hilo

Tonight: Mostly cloudy with scattered showers. Lows 65 to 71 near the shore to 53 to 60 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 80 to 86 near the shore to 67 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 63 to 70 near the shore to 51 to 58 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Kona

Tonight: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows around 73 near the shore to 50 to 55 near 5000 feet. North winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 87 near the shore to 69 to 74 near 5000 feet. West winds 10 to 15 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows around 73 near the shore to around 51 near 5000 feet. West winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Waimea

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 64 to 72 near the shore to 57 to 64 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 65 to 86. East winds 10 to 25 mph. Chance of rain 20 percent.

Sunday Night: Breezy. Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 55 to 63 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Kohala

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 64 to 72 near the shore to 57 to 64 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 65 to 86. East winds 10 to 25 mph. Chance of rain 20 percent.

Sunday Night: Breezy. Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 55 to 63 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly clear. Breezy and haze. Lows around 74 near the shore to around 54 near 5000 feet. East winds 10 to 20 mph.

Sunday: Mostly sunny. Breezy. Haze through the day. Isolated showers in the afternoon. Highs around 88 near the shore to around 70 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Breezy. Isolated showers in the evening. Haze through the night. Lows around 73 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with scattered showers. Lows 65 to 71 near the shore to 53 to 60 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 80 to 86 near the shore to 67 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 63 to 70 near the shore to 51 to 58 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Waikoloa

Tonight: Mostly clear. Haze. Lows around 74 near the shore to around 55 above 4000 feet. East winds 10 to 15 mph.

Sunday: Mostly sunny. Breezy. Highs 85 to 93 near the shore to 69 to 77 above 4000 feet. Northeast winds 10 to 20 mph.

Sunday Night: Partly cloudy with isolated showers. Lows around 74 near the shore to 50 to 55 above 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trade winds will gradually strengthen through Sunday with mostly dry conditions expected through the weekend. A weak upper level trough approaching the area will likely bring an increase of showers starting Monday and will likely persist through at least the middle of next week. Bands of moisture could produce some showery weather at times especially across windward and mountain locations.

Discussion

This afternoon's radar and satellite imagery shows stable stratocumulus clouds across many windward and mountain areas with very little rainfall across the state. Soundings from Lihue and Hilo show a strong inversion near 5000 feet, which is limiting any vertical development this afternoon.
Going into Sunday, dry and stable conditions should continue with trade winds strengthening across the state. Due to the winds strengthening and the relatively dry conditions in place, elevated fire weather concerns are expected for Sunday, especially over Maui County and parts of the Big Island, where fuels are drier and the winds are stronger than the western half of the state. It is urged that everyone remains mindful of activities that could produce a spark when working or recreating outdoors.
Starting next week Monday, an increase of showers is expected as an upper level trough approaches the state. Enhanced trade wind showers with periods of showery weather will be possible starting Monday and likely persisting through at least the middle of the week. No significant rainfall is expected, but it just might be enough rainfall to alter your outdoor plans if caught in these bands of moisture that will be moving through the island chain at times. Showers will likely be most active over windward and mountain areas on Tuesday or Wednesday of next week.
In the long range, the upper level trough should move westward and away from the state during the second half of next week with a ridge building in from east. Passing showers will likely still persist, but the showers should be less frequent and less intense than the showers during the first half of the week. Trades will also gradually decrease Tuesday into Wednesday as the high weakens to our north. Moderate to locally breezy trades are expected by Wednesday.

Aviation

High pressure situated well northeast of the islands will build through tomorrow, resulting in breezy trades this afternoon that will strengthen into Sunday. Expect limited shower activity across the islands under a drier, more stable airmass. However, clouds and a few showers will still favor windward and mountain areas and may cause brief periods of MVFR conditions. Otherwise, VFR conditions are expected to prevail.
AIRMET Sierra for tempo mountain obscuration is in effect for windward portions of Oahu and Kauai as MVFR ceilings persist this afternoon.
AIRMET Tango will likely be needed this evening or overnight as the low level winds increase under the strengthening inversion.

Marine

High pressure anchored northeast of the islands will drive fresh to strong trades tonight through Sunday before easing slightly early next week. The Small Craft Advisory has been expanded accordingly.
Small, medium period S swell maintains below average surf until Monday when a moderate, long period S swell fills in. This swell peaks Tuesday near the High Surf Advisory threshold. At the same time, king tides will be reaching their peak leading to potential for coastal flooding of susceptible areas. The threat for coastal flooding will be exacerbated by the ongoing S swell.
Strong trades maintain short period fresh swell and plenty of chop along E facing shores. Surf remains very small N and W through the period.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 PM this evening to 6 PM HST Sunday for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov