THE WEATHER BEAT · OCT 26

A Flood Watch for every main Hawaiian island from Tuesday, with 2 to 8 inches of rain forecast through Thursday

NWS Honolulu expects a stalled tropical trough to bring 2 to 8 inches Tuesday to Thursday; Tropical Storm Olana weakens to the southwest.

By the Weather Rock October 26, 2026, 9:53 a.m. · 7 min read ShareCopy link

A wet week coming for the islands

Hawaii usually gets its rain from the trade winds: steady showers on the windward slopes and dry leeward coasts. The forecast for this week is different. At 3:05 a.m. HST Monday the Honolulu office issued a Flood Watch for all main islands, from Niihau and Kauai to the Big Island. It covers the whole chain, leeward zones included, from Honolulu Metro and the Ewa Plain on Oahu to Kona and Big Island East.

The office's morning discussion explains the setup. A large low sits about 800 miles northeast of the state. A trough runs southwest from it toward the islands, and the office expects that trough to stretch toward what is left of Olana and then drift north over Hawaii. It says the air moving in carries precipitable water "close to 2.5 inches," that the trough will "remain nearly stationary over the area through the end of the week," and that "a series of small lows will form with one or more potentially moving over the state." The office is plain about the limits of the forecast: "Models still show disagreement on timing and locations of these features. This makes the uncertainty higher than normal."

The watch text gives the risk. Heavy showers and a few thunderstorms "with intense rain rates" may begin Tuesday. Flood-prone roads and low areas may close as streams rise, and "urban areas may receive more significant flooding and property damage due to rapid runoff." The office says the watch may be extended past Wednesday. Its Monday forecast calls for trade winds to return this weekend, with rain still above normal.

The watch covers the zones that hold Honolulu, Hilo, Kailua-Kona, Kahului, Kaunakakai and Lanai City, and the forecast page for each town updates on its own.

*Source: NWS Honolulu Flood Watch and Area Forecast Discussion on api.weather.gov, read at 13:50Z to 13:55Z October 26.*

Olana, and two readings of its path

The Central Pacific Hurricane Center's Advisory 4, at 11 p.m. HST Sunday, put Olana about 490 miles west-southwest of Johnston Island. It had 40 mph winds and was moving east at 7 mph. The advisory lists no coastal watches or warnings, and under hazards affecting land it says "None." The discussion calls the 35 knot intensity something that "could be generous" and forecasts Olana to become a remnant low by 36 hours and to dissipate by day 3. "Olana is expected to dissipate prior to reaching Johnston Atoll."

Honolulu's morning discussion describes Olana's part in the island forecast in different words. It says a trough to the northwest "will sag southeast helping pull Olana toward the islands," and that Olana "is expected to weaken into a tropical depression and stay to the west of the islands Tuesday." The two offices agree that Olana weakens. Where they differ is in how they describe its motion, and we report both as written. The rain in the Flood Watch comes from the trough, not from a landfall.

*Source: CPHC Tropical Storm Olana Advisory 4 and Discussion 4, issued by NWS National Hurricane Center Miami, read on api.weather.gov at 13:52Z October 26.*

Last night's numbers, checked

Sunday evening's story left two river numbers to check. Pueblo's 2:48 a.m. MDT warning had the Rio Grande at Alamosa, Colorado, at 9.9 feet at 2:30 a.m. That is above the 9.6 foot crest forecast on Sunday afternoon. The new forecast is a crest of 10.0 feet this morning. The product now compares that crest to 10.0 feet on May 23, 1948. Sunday's product had compared it to 9.9 feet on June 5, 1948. Near Bernardo, New Mexico, Albuquerque's 7:44 p.m. MDT warning forecast the Rio Puerco to crest at 24.2 feet just after midnight. It also said the river read 20.0 feet at 3 p.m. Sunday, with "no reliable observations available thereafter." So that crest has not been read yet.

*Source: NWS river Flood Warnings on api.weather.gov, read at 13:55Z October 26.*

What the reader can check

Honolulu's range is 2 to 8 inches between Tuesday and Thursday. The Thursday discussion and the rain totals that follow it will show where in that range the islands landed, and whether the watch was extended. The Weather School page on watches, warnings and advisories explains why a watch means flooding is possible and is not a promise that it will happen.

This is a summary, not emergency information. For live warnings see weather.gov and your local officials.

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