textproduct: Honolulu

SYNOPSIS

Tropical Storm Nolo will intensity to a hurricane as it drifts northward toward Big Island during the next couple of days. Rainfall along the northern edge of the system will gradually increase across the Big Island and Maui, leading to the potential for significant to locally catastrophic flooding mainly on windward and southeast Big Island. While uncertainty in the track of the tropical cyclone is higher than normal, Big Island remains under a Hurricane Watch with the potential for damaging winds Friday and Saturday. Nolo is expected to move westward on Sunday, but all interests in Hawaii should monitor the progress of the system as impacts could persist through the weekend.

SHORT TERM UPDATE

The forecast remains on track this evening with no changes. Tropical Storm Nolo was located nearly 300 miles south of Big Island and is expected to intensify as it makes a slow turn northward overnight and Thursday. Deeper moisture along the northern flank of Nolo continues to move across Big Island on a moderate to locally breezy trade wind flow. Numerous locations on windward Big Island have received in excess of an inch of rainfall during the past 12 hours, though recent data show that hourly rainfall is down below 1 quarter of an inch per hour. For tonight, focus will remain on flood potential on Big Island.

PREV DISCUSSION

Issued at 457 PM HST Wed Sep 23 2026 Radar and satellite show numerous showers over Big Island, along with a large band of showers to its south which is being heavily influenced by Nolo. Elsewhere, conditions are dry. Skies were mostly cloudy on Big Island and in windward/mauka areas on other islands. Winds were averaging 10-20 mph, with gusts 30-35 mph in the usual gusty places.

The latest update on Nolo has it located near 14.7N and 155.9W (about 350 miles south of Hilo) with maximum winds of 45 mph. It was moving WNW (285 degrees) at 6 mph. The forecast calls for it to move generally N tonight, then NNE Thursday through Thursday night. It is forecast to turn to the NW and then W Friday into Saturday. There is uncertainty on exactly when those Friday into Saturday turns will occur, and therefore how close it will get to the Big Island.

The forecast rainfall on Big Island remains 20-30 inches, with isolated amounts to 35 inches. On Maui, we expect 10-15 inches, with isolated amounts to 15 inches. Winds will begin to increase significantly Thursday night into Friday, and wind advisories or warnings will likely be needed outside of the Hurricane Warning area.

The current forecast has only minor changes. We slightly increased the rainfall totals on Maui and the Big Island, increased the chance of rain in several areas, and made small edits to winds. Unless/until the track changes significantly, the forecast is rather stable for now.

AVIATION

Breezy and gusty trades for the next few days. Tropical Storm Nolo is about 300 miles south of the Big Island and moving WNW at 5 kt. As this gets closer expect winds to increase especially across the eastern end of the state. Showers will increase and be heavy at times. TSTMs are possible but confidence is low on exactly where as such elected not to include those in the TAFs at this time. While conds are MVFR/VFR now, conds will deteriorate as Nolo nears. LIFR to MVFR possible across the Big Island with areas on the western end of the state being MVFR/VFR.

TC SIGMET Series Oscar covers Tropical Storm Nolo.

AIRMET Sierra is in effect for mtn obsc for Maui and the Big Island. Expect this to expand as Tropical Storm Nolo gets closer.

AIRMET Tango is in effect for low level turb lee of terrain.

MARINE

Issued at 457 PM HST Wed Sep 23 2026 Main changes with the afternoon package are an expansion of the Small Craft Advisory (SCA) for a combination of winds and seas over the next couple of days. The SCA continues for typical windier areas tonight, and expands to the central waters tomorrow, and then to Kauai waters Friday. Friday morning the waters near the Big Island transition from a SCA to the Hurricane Watch for Tropical Storm Nolo.

Tropical Storm Nolo is moving slowly northward towards the islands, and will bring increasing swell, winds and rainfall beginning Thursday. While waters near the Big Island are under a Hurricane Watch now, additional waters may need to be added to tropical watches or warnings, depending on the exact track of Nolo is determined with future model runs. Nolo is currently expected to continue on a northward trend, before a turn to the west, but is expected to impact the coastal waters through the weekend.

The current south-southwest swell continue to fade, and a moderate southwest swell will build in Friday, and last into the weekend, with surf peaking near advisory levels. Tropical Storm Nolo is expected to strengthen, and will likely produce a southerly swell that will bring large and rough surf particularly to the south facing shores of the Big Island.

A new small northwest swell will fill in this weekend keeping surf slightly elevated along north and west facing shores. East facing shores will maintain rough, short period wind waves generated from the breezy trade winds.

FIRE WEATHER

Winds will steadily strengthen over the next few days as Nolo moves nearer, creating moderate fire weather conditions mainly over drier leeward areas from Kauai to Maui County. Rainfall will increase each day through Saturday, mitigating to some extent the stronger winds. The inversion will not be present over the eastern end of the state through this weekend.

HFO WATCHES/WARNINGS/ADVISORIES

Flood Watch through Saturday afternoon for Big Island East-Big Island Interior-Big Island North-Big Island South-Big Island Southeast-Big Island Summits-Haleakala Summit-Kahoolawe-Kipahulu- Kohala-Kona-Lanai Leeward-Lanai Mauka-Lanai South-Lanai Windward- Maui Central Valley North-Maui Central Valley South-Maui Leeward West-Maui Windward West-Molokai Leeward South-Molokai North- Molokai Southeast-Molokai West-Molokai Windward-South Haleakala- South Maui/Upcountry-Windward Haleakala.

Hurricane Watch for Big Island East-Big Island Interior-Big Island North-Big Island South-Big Island Southeast-Big Island Summits-Kohala-Kona.

Hurricane Watch for Alenuihaha Channel-Big Island Leeward Waters- Big Island Southeast Waters-Big Island Windward Waters.

Small Craft Advisory from 6 AM Friday to 6 PM HST Saturday for Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters.

Small Craft Advisory from 6 AM Thursday to 6 PM HST Saturday for Kaiwi Channel-Kauai Channel-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.

Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay- Pailolo Channel.

Small Craft Advisory until 6 AM HST Friday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.