Hilo

Tonight: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 49 to 56 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs 74 to 81 near the shore to around 65 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with showers likely. Lows 62 to 69 near the shore to 49 to 56 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly clear with isolated showers. Lows around 70 near the shore to 43 to 51 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. North winds up to 10 mph. Chance of rain 20 percent.

Tuesday Night: Mostly clear. Lows around 71 near the shore to 43 to 51 near 5000 feet. East winds around 10 mph.

Waimea

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 62 to 71 near the shore to 54 to 60 near 3000 feet. East winds 10 to 25 mph. Chance of rain 40 percent.

Tuesday: Windy. Mostly sunny with scattered showers. Highs 72 to 79 near the shore to 68 to 76 near 3000 feet. East winds 15 to 35 mph with gusts to 60 mph. Chance of rain 40 percent.

Tuesday Night: Windy. Partly cloudy with scattered showers. Lows 62 to 70 near the shore to 54 to 60 near 3000 feet. East winds 15 to 35 mph with gusts to 60 mph. Chance of rain 50 percent.

Kohala

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 62 to 71 near the shore to 54 to 60 near 3000 feet. East winds 10 to 25 mph. Chance of rain 40 percent.

Tuesday: Windy. Mostly sunny with scattered showers. Highs 72 to 79 near the shore to 68 to 76 near 3000 feet. East winds 15 to 35 mph with gusts to 60 mph. Chance of rain 40 percent.

Tuesday Night: Windy. Partly cloudy with scattered showers. Lows 62 to 70 near the shore to 54 to 60 near 3000 feet. East winds 15 to 35 mph with gusts to 60 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly clear. Breezy. Lows around 71 near the shore to around 48 near 5000 feet. Northeast winds 10 to 20 mph.

Tuesday: Sunny and breezy. Highs around 84 near the shore to around 66 near 5000 feet. East winds 10 to 25 mph.

Tuesday Night: Mostly clear. Windy. Lows around 71 near the shore to around 49 near 5000 feet. Northeast winds 10 to 30 mph.

Puna

Tonight: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 49 to 56 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs 74 to 81 near the shore to around 65 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with showers likely. Lows 62 to 69 near the shore to 49 to 56 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly clear. Lows 68 to 73 near the shore to 47 to 53 above 4000 feet. East winds up to 15 mph.

Tuesday: Sunny and windy. Isolated showers in the afternoon. Highs 81 to 87 near the shore to 66 to 72 above 4000 feet. Northeast winds up to 35 mph increasing to 10 to 35 mph in the afternoon. Gusts up to 60 mph. Chance of rain 20 percent.

Tuesday Night: Mostly clear. Windy. Lows 69 to 74 near the shore to 48 to 53 above 4000 feet. East winds 10 to 30 mph with gusts to 50 mph.

Detailed Forecast

Synopsis

Fairly dry conditions continue through much of the week as trade winds steadily strengthen to strong speeds by Wednesday and Thursday. Wind speeds will then start a gradual decline into the moderate to locally breezy range from Thursday night into next weekend. An upper level low will develop and pass just south of the Big Island from Wednesday through Friday. This upper level disturbance may enhance rainfall coverage over the eastern half of the state mainly around Thursday night into Friday.

Discussion

Latest radar and satellite imagery shows mostly dry conditions across the state this afternoon with a few light sprinkles across windward and mountain areas. Over the next 24 to 36 hours, trade winds will gradually strengthen with widespread strong trade winds expected by Tuesday night. The stronger trade winds could bring a slight uptick of showers especially during the early mornings and nighttime hours. But generally rainfall amounts should remain light through most of the week.
The main concern for this upcoming week will be the strong trade winds that could elevate fire weather concerns for leeward areas. See the FIRE WEATHER section below for more details. Otherwise, we could see winds approach the wind advisory threshold as early as Tuesday afternoon for some of the windier areas around Maui County and the Big Island, but more likely on Wednesday as the high strengthens northeast of the state. Wednesday and Thursday looks to be the windiest days, where we could see wind gusts approach 50 mph for the windy areas such as Kohala and Kau districts of the Big Island and parts of Maui County. Wind Advisories will also be possible for the rest of the state as well, but at this time confidence remains highest for the windier areas of Maui County and the Big Island.
As for the summits of the Big Island, a Wind Advisory is now in effect through tonight. Winds may hold near borderline advisory thresholds through Tuesday. Another round of High Wind Warning level winds will be possible on Wednesday.
An upper level low passing south of the state Wednesday through Friday could bring an increase of showers over parts of windward Big Island and Maui especially around Thursday night into Friday. At this time, it looks like the main instability and moisture should pass south of the state, but a slight shift northward could bring more enhanced showers. Stay tuned for more details.

Aviation

Primary aviation concern today has been the deep layer of moderate to severe turbulence over the islands. This corridor of turbulence has largely shifted east of the immediate area in concert with a progressive mid/upper trough. It is still covered by SIGMET Whiskey while AIRMET Tango remains in effect for the islands for tempo mod turb in the mid-upper levels. In addition, strengthening trades warranted another issuance of AIRMET Tango for lee turb aob 8kft.
Island weather remains quiet otherwise as breezy trades tend to strengthen through the period. A typical trade wind pattern will prevail during this time with clouds and showers focused windward and mauka, though dry air and high stability will tend to limit shower coverage.
AIRMET Tango for lee turb aob 8kft in effect.
AIRMET Tango for moderate turb 140/FL420 in effect.
SIGMET Whiskey for severe turb in effect over the eastern waters and the Big Island and extending northeastward for FL250/FL420.

Marine

Easterly trade winds will continue strengthening to become fresh to strong across most waters by Tuesday, then near-gales by Wednesday as a surface ridge establishes itself to the north. Meanwhile, a north-northwest swell moving through the islands, and a reinforcement on Tuesday, will elevate seas to at least 10 feet across the remaining coastal waters. Therefore, the Small Craft Advisory that was previously in effect for portions of the coastal waters has been expanded to include the entire area with this afternoon's forecast updates.
Surf along north and west-facing shores continues to sharply increase this afternoon as a north-northwest swell builds down the island chain. Observations from nearshore buoys at Hanalei and Waimea have significantly increased over the past few hours as the swell moves in. This swell, which is running well above guidance, will peak tonight into Tuesday, but will be followed by another northwest reinforcement by Tuesday afternoon. A High Surf Advisory (HSA) remains in effect for north and west facing shores of Niihau, Kauai, Oahu, and Molokai, and north facing shores of Maui, and has been extended through Tuesday night. A slight downward trend is expected during the second half of the week, with surf holding steady near or slightly below seasonal averages by Friday into the weekend.
Surf along south-facing shores will gradually subside on Tuesday. Seasonal conditions are expected to return midweek, with smaller southeast and south-southwest swells contributing to surf conditions
Surf along east-facing shores will rise through the week as trade winds strengthen locally and expand upstream across the eastern Pacific

Fire weather

Trade winds strengthening over the next few days will increase fire weather concerns this week especially on Wednesday and Thursday where the trades are expected to be at their strongest. Relative humidity (RH) levels should get near critical thresholds over some of the windier leeward areas by Wednesday afternoon. Red Flag Warnings will be a possibility (Wednesday and Thursday) and the only limiting factor for us to issue a Fire Weather Watch at this time is the minimum humidities being borderline critical. We will watch the humidities on Tuesday to give us a better idea of the potential of Red Flag Warnings on Wednesday.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Wednesday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Wind Advisory until 6 AM HST Tuesday for Big Island Summits.
Small Craft Advisory until 6 PM HST Wednesday for all Hawaiian waters,

Big Island Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Big Island Helicopter Tours today!

Data Courtesy of NOAA.gov