Honolulu in October: Weather, Sea Temperature and How the Month Compares to September and November

HONOLULU · OCTOBER · OAHU’S LEEWARD SHORE

Honolulu does not do seasons the way the mainland does, but October moves the dials. The airport gauge records an average high of 86.9°F, the sea off the south shore sits at 80.7°F, and the 15th brings 11 hours 41 minutes of daylight, which means the last swim of the day ends earlier than it did in August. For a trip already pointed at Waikiki, the useful question is what these four weeks give and what they take away.

October is also the month that decides how much rain gets into an itinerary: 1.51 inches at the airport, against 0.88 inches in September and 2.25 in November. Read those three figures before you pick flight dates, and the beach days mostly look after themselves.

On this page

• Average high and rain days in October86.9°F, 1.51 inches, 2.6 wet days
• Sea temperature for swimming80.7°F off the south shore
• Crowds and when to book a hotelWhat the data covers, and what it doesn’t
• What to do in Honolulu in OctoberWaikiki, Ala Moana, Hanauma Bay, Diamond Head
• A two-day plan for the monthSunrise 6:26 a.m., sunset 6:07 p.m.
• October vs September vs NovemberHow the three months compare, in figures
• Is October a good month to visit?Who should book it, who should shift

Two data sets carry the month, and they are not the same kind of measurement. NOAA’s 1991-2020 normals come from a real thermometer and a real rain gauge at Honolulu International Airport. The water figure comes from a marine model averaged over 2015-2024. Neither one speaks for the windward side of Oahu.

Honolulu weather in October: average highs, lows and rain days

The normals above are NOAA NCEI’s 1991-2020 series for station USW00022521, the gauge at Honolulu International Airport. October runs an average high of 86.9°F, an average low of 73.9°F and 1.51 inches of rain. Every figure here is measured on the leeward south shore. The windward coast and the ridges behind the city take several times that rainfall, and this instrument never sees a drop of it. For a hotel in Waikiki or Ala Moana, the numbers travel the few miles fine. Over the Ko’olau, they stop applying.

Measurable rain lands on 2.6 days in an average October, about one day in twelve. Since 1.51 inches arrives across fewer than three days, most of the month’s rain falls in a small number of hours rather than drizzling across the calendar. Plan outdoor days normally and keep a single indoor option in reserve, not a rain week.

Thirteen degrees separate the 86.9°F high from the 73.9°F low, and the low arrives near dawn rather than at midnight. Nothing in that range calls for a jacket. What it does call for is one light layer for restaurants, rental cars and hotel lobbies, where the air conditioning runs harder than the weather ever will.

On October 15 the sun rises at 6:26 a.m. and sets at 6:07 p.m. local time, giving 11 hours 41 minutes of daylight. That reshapes a beach day more than the temperature does: the last comfortable swim lands around 5 p.m., dinner happens after dark, and any climb you want to do in cool air starts before 8 a.m. Travelers flying in from the East Coast wake up early for the first two mornings anyway, which for once works in the itinerary’s favor.

Can you swim in Honolulu in October? Sea temperature and what it feels like

The sea surface off Honolulu averages 80.7°F in October according to the Open-Meteo Marine API, taken as the mean of daily maxima over 2015-2024. That last detail matters. It is the warm end of each day’s water, a shade above what a 24-hour mean would give, and it comes from a model rather than a thermometer somebody reads at the pier. Treat 80.7°F as the top of the range.

At that temperature the ocean is warmer than the average October night on land, which bottoms out at 73.9°F. Nobody stands in the shallows negotiating with it. The figure supports the long, lazy uses of the water: an hour of snorkeling without shivering, kids who stay in until they are told to come out, a 5 p.m. swim that costs you nothing for the evening. A rash guard here does more against the sun than against the cold.

Wind and swell are the hole in the record. No wave heights and no trade wind figures for October were read, so none are quoted. Oahu’s shores behave differently from one exposure to the next, and the move before a snorkeling morning or a boat trip is the National Weather Service surf and marine forecast for Oahu, checked the night before.

How busy is Honolulu in October, and when should you book?

October sits in the calendar gap between the summer school break and the Thanksgiving-to-New-Year block. That is a fact about the calendar, not about rates. No hotel occupancy series and no monthly room-rate data were read, so October gets no ranking against the other eleven months and no claim about where prices sit. What the figures do support is a date lever: shift the trip by four weeks and you move 1.5°F of afternoon heat and 0.2°F of water, and very little else.

Booking follows from that. If the vacation is built around the ocean, any week of October delivers within a fraction of a degree of any other, so choose dates on airfare and flight times rather than on the forecast. If it is built around one beachfront hotel or a rental car for the windward side, those are the two decisions worth locking early. As editorial judgment rather than measured data: on a four-night trip, reserve the car before the room.

No lodging tax rate was read, so no percentage appears here. Price it from the booking page itself, where the tax line and any resort or parking fee show up on the final screen, and compare two hotels on that total rather than on the headline nightly rate.

The one place where money changes the month is the car. The 1.51-inch figure belongs to a gauge on the leeward shore, and the hours the mountains catch are not the hours Waikiki gets. A car turns that geography into a choice on a gray morning instead of a default museum afternoon. Airport counters and city hotel parking both cost more than the bus, and on a short trip it is the upgrade the weather repays.

Things to do in Honolulu in October

October’s combination is specific: water at 80.7°F, air that has dropped 1.5°F off September’s average high, and 11 hours 41 minutes of daylight on the 15th. That buys a full ocean day with the top of the afternoon slightly less punishing than it was six weeks earlier, plus enough light for a climb before dinner without carrying a headlamp.

Waikiki, Ala Moana Beach Park and Hanauma Bay all front the same south-shore water the 80.7°F figure describes, and Diamond Head climbs straight out of it. Entry fees, reservation windows and closing times for Hanauma Bay and Diamond Head State Monument were not part of the data read here, so no price and no hour is quoted. Both run on state and city systems that change, and both should be priced and reserved on the official site before a day is built around them.

The swim itself barely changes across the fall: 80.5°F in September, 80.7°F in October, 79.0°F by November, all from the same marine series. The climb does change. A Diamond Head afternoon in October sits 1.5°F below September’s average high and 2.8°F above November’s, which is the whole seasonal difference at a place whose staircase is identical all year.

The free part of an October day is the part the numbers cover. Public beach access along the south shore costs nothing, nobody charges for the 80.7°F water, and the 6:07 p.m. sunset on the 15th needs no ticket. No free-admission days for Honolulu museums appear in our data, and no October event dates either, so none are listed. Check the venue calendars once your dates are fixed.

Honolulu in October: a two-day itinerary

Day one runs on the light. Sunrise at 6:26 a.m. puts you on the sand or on the crater stairs while the air is nearest its 73.9°F overnight low. Breakfast by nine. Museum, lunch and shaded streets from eleven to two, while the 86.9°F average high does its work. Into the water from 3 p.m., when the sea is at the warm end of its daily curve and 80.7°F is closest to true. Out by 5:30 and at a table for the 6:07 p.m. sunset.

Day two crosses to the windward side by car, because the leeward gauge stops describing anything the moment you pass the Ko’olau. If the sky turns, the arithmetic helps: 2.6 wet days out of 31 means an outdoor plan survives most Octobers. Keep Bishop Museum or the Honolulu Museum of Art as the indoor swap and push the swim to the other afternoon. Pearl Harbor runs its own reservation system and was not priced.

Honolulu in October vs September and November

Across the three months the air falls steadily while the rain climbs: 88.4°F and 0.88 inches in September, 86.9°F and 1.51 inches in October, 84.1°F and 2.25 inches in November, with wet days going 2.2, 2.6, 2.9. The water moves the other way first, 80.5°F, then 80.7°F, then 79.0°F. Air normals come from NOAA’s 1991-2020 station series; the sea figures are the marine model’s 2015-2024 daily maxima, a different instrument over a different decade.

Shift four weeks earlier and you gain 1.5°F of afternoon heat and shed 0.63 inches of rain, the clearest trade on the table (September in detail). Shift four weeks later and November takes 2.8°F off the high and 1.7°F off the water, charges 2.25 inches of rain, and gives back the coolest afternoons of the three for anyone who walks all day.

Is October a good time to visit Honolulu?

Yes for anyone whose trip is built around the ocean: 80.7°F is the warmest water of these three months, and 2.6 wet days is a small bill for it. No for anyone who needs a guaranteed dry fortnight for a wedding or a shoot, because 1.51 inches is a leeward airport figure and the island’s real rain falls where that gauge is not.

When the answer is no, September is the month to move to: 0.88 inches, 2.2 wet days, and water within 0.2°F of October’s. The cost is 88.4°F afternoons, which is where the heat stops being pleasant for a walking vacation. November runs the other way at 84.1°F and 2.25 inches, and it suits a trip weighted toward town, food and short outings.

What October alone holds among the three is the pairing: the warmest water of the set at 80.7°F under afternoons already 1.5°F off September’s peak.

The last word

Choose the dates on the water and the light rather than on the rain column. An inch of rain or more falls on 0.3 of a day in an average October, which works out to one genuine downpour day roughly every third year, and the instrument counting it stands at Honolulu International Airport on the dry side of the island. Take the car across the Ko’olau once and see what that gauge never records. If the figures push you a month either way, the twelve-month view handles the rest.

Sources & data for this guide

• October normals: high 86.9°F, low 73.9°F, 1.51 in · NOAA NCEI monthly normals 1991-2020, station USW00022521, Honolulu International Airport · checked Sep 15, 2026
• Rain-day counts: 2.6 days at 0.10 in or more, 0.3 day at 1.00 in or more · NOAA NCEI, same station and period · checked Sep 15, 2026
• September and November normals, including wet-day counts · NOAA NCEI, same station and period · checked Sep 15, 2026
• Sea surface 80.7°F (Oct), 80.5°F (Sep), 79.0°F (Nov), mean of daily maxima 2015-2024 · Open-Meteo Marine API · checked Sep 15, 2026
• Daylight 11h 41m on October 15, sunrise 16:26 UTC and sunset 04:07 UTC converted to local time · sunrise-sunset.org · checked Sep 15, 2026
• Editorial admission: no lodging tax rate, no hotel occupancy or room-rate series, no ticket prices for Honolulu sites and no October event dates were read for this guide, so none are quoted · fees and hours change, price them with the operator when you book.