textproduct: Honolulu

SYNOPSIS

Breezy trade winds today will become strong and gusty as early as tomorrow afternoon. Showers will generally favor windward and mauka areas, particularly during the overnight through early morning hours each day. Hurricane Lowell is about 500 miles southeast of the Big Island early this morning, and is forecast to pass south of the Big Island late Wednesday into Thursday. Winds are expected to remain strong and gusty through Friday as Lowell passes south of the islands. The forecast remains uncertain for Labor Day weekend, with the potential for Lowell and Karina in the the vicinity of the state.

SHORT TERM UPDATE

Trade wind showers were moving west across windward and mauka areas of most islands this morning, with rainfall amounts from a few hundredths to a few tenths of an inch. Trades are expected to gradually increase in speed. They may reach advisory level Wednesday afternoon in the typical windy spots, but we will await further model runs before deciding whether to issue.

Otherwise, all eyes remain glued to the hurricanes in the area. Lowell and Karina's current forecast tracks from the NHC keep them away from the state for the next 5 days, but there is significant uncertainty in the forecast after that. Models continue to depict Lowell turning north after it moves west of the state. The timing of that turn is a huge question mark at this time. The majority of the runs show it moving by to the west of the main Hawaiian islands. If it ends up heading for the main part of the state (low probability solution for now), the timing would indicate passage on the 7th or 8th. See the previous discussion for additional details.

PREV DISCUSSION

Issued at 342 AM HST Tue Sep 1 2026 No significant changes to the forecast this morning. Although the PoP grid was adjusted, little change through Thursday night. For Friday there is a marked decrease in shower activity over the islands as Lowell will have moved further from the islands.

Clouds and showers continue to be carried in on the trade wind flow, and as a result are focused over the windward and mauka areas. A surface trough about 350 miles east of the islands will continue to move towards the islands today and weaken. Moisture from that trough will reach the islands tonight, helping to boost shower activity tonight.

Tropical Storm Lowell is about 550 miles southeast of the Big Island early this morning, and the latest forecast from the National Hurricane Center (NHC) has Lowell strengthening to a hurricane within the next 12 hours. The latest track and cone for Lowell has the system passing south of the islands Wednesday night through Friday. Outer rainbands and moisture from Lowell could begin to spread across the islands today, increasing chances of passing trade wind showers, however the bulk of moisture will likely pass south of the state. Additionally dewpoint temperatures are expected to exceed 70 degrees, which will make the atmosphere muggier than normal. Trade winds will stay breezy due to a strong surface high remaining far north of the area.

Overall expect an uptick in passing showers over the next few days, due to the moisture from the trough mentioned above tonight, and moisture loosely associated with Lowell passing through the state.

The latest forecast from the NHC has Lowell passing a little over 300 miles south of the Big Island Wednesday night into Thursday as a category 3 Major Hurricane. While probabilities for tropical storm force winds remain low over the state, the tightening of the pressure gradient over the islands will likely produce very windy and gusty trade winds as early as Wednesday afternoon through Friday. Winds could reach advisory thresholds with wind gusts over 50 mph possible during this time.

As we head into the weekend, as Lowell exits, our focus will shift more to Hurricane Karina which is currently about 1500 miles east of the Big Island. The latest forecast from NHC for Karina brings it about 600 miles east of the Big Island on Saturday. We will continue to monitor Karina over the coming days to discern its potential impacts on the state.

The forecast spread drastically increases over the Labor Day weekend into early next week as an upper level trough/low develops north of the state. Several models show Lowell taking a sharp northward turn over the weekend. While confidence has increased on Lowell passing south of the state during the week, the forecast still remains very uncertain over Labor day weekend due to the northward turn in the various models. Also during this time, we could see Karina within the vicinity of the islands late this weekend. Please keep an eye out on the hurricanes.gov page for the official NHC forecast for Lowell and Karina.

AVIATION

18Z TAFS - Active showers this morning impacting Maui and Big Island bringing MVFR conditions and locally IFR in heaviest showers. Otherwise, moderate trade winds will persist through this period. Diurnal trends of MVFR conditions and brief showers through the trades will generally favor windward exposures, mauka and higher terrain. Otherwise, VFR conditions will prevail. Tropical Cyclone Lowell is forecast to pass far south of the island chain the next few days. On this track, late week trade winds will strengthen as the pressure gradient tightens between Tropical Cyclone Lowell and high pressure to the far north.

AIRMET Sierra is in effect for mountain obscuration for the north through east districts of Big Island due to persistent low clouds and shower coverage. AIRMET Sierra will remain in effect for Big Island through this morning.

AIRMET Tango remains in effect for moderate low level turbulence south through west downstream of high terrain. AIRMET Tango will likely be in effect for the foreseeable future.

MARINE

A strong surface high will remain nearly stationary far north of the Hawaiian Islands this week, keeping fresh to locally strong trade winds in place. A Small Craft Advisory (SCA) remains in effect for the typically windy waters as a result of the locally strong trades. The SCA will likely need to be expanded as trade winds gradually strengthen across the state to strong to possible locally gale force late Wednesday through Thursday as Lowell passes far south. The offshore waters will likely see tropical storm conditions over the south waters as the core of hurricane force winds remains just outside the area Wednesday into Thursday. There is still some uncertainty with the forecast track of Lowell, especially this weekend and early next week as the cyclone begins to gain latitude, which will have significant impacts on the wind, wave, and surf forecast for the region. Adding to the extended forecast uncertainty will be the approach of Hurricane Karina from the east.

A moderate, long-period south swell arrives today. This swell will build through the day and overnight before peaking on Wednesday, bringing surf heights to just below advisory thresholds. This swell will then gradually decline through the rest of the week. A small, medium-period south southeast swell energy from Lowell could start filling in across south and southeast shores. South shore surf will likely remain elevated near to just advisory levels through at least Friday. Beyond that point, the surf forecast is highly dependent on the eventual track and intensity of Lowell, which has the potential to be a significant source of south to southwesterly swell through this weekend and into next week depending on how sharply and quickly the cyclone turns to the north.

Trade wind swell energy will keep rough, choppy surf along all east-facing shores through the coming week. Tonight, a small, medium- period east swell arrives from Hurricane Karina that will build through the week and could push east shore surf to advisory thresholds by this weekend and into next week.

FIRE WEATHER

Issued at 342 AM HST Tue Sep 1 2026 Breezy trades today are expected to strengthen further as early as Wednesday afternoon through Friday as Tropical Storm Lowell passes south of the islands as a hurricane. Strong gusty winds over 50 mph will be possible across select areas during this time. While fuel conditions are not at critical levels due to abundant rainfall we have received over the past several weeks, moderate fire danger will be possible for areas mainly due to very windy conditions. Dewpoints are expected to increase in the upper 60s and low 70s by Tuesday afternoon and hold through the week, keeping minimum humidities in the 50s for the most part. A few leeward areas could still see humidities down into the mid 40s especially on Thursday as a pocket of dry air moves in. The exact track of Lowell remains uncertain and thus potential for meaningful rainfall remains uncertain at this time. The inversion will hover between 5500 ft and 6500 ft over the next couple of days.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 PM HST Wednesday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.