Best Time to Visit Honolulu: Weather, Sea Temperature and the Quiet Months

HONOLULU · BEST TIME TO VISIT · 21.3° N

Honolulu’s year moves less than almost any American city’s. Measured by average highs, 8.3°F separates August (88.8°F) from January and February (80.5°F), and the ocean off the south shore never averages below 76°F in any month. So the question is rarely whether the weather will cooperate. It is which weeks buy you the driest ground, the warmest water and the longest evening.

Rain is what actually swings. The five months from November through March collect 10.57 inches between them at the airport gauge, while the six from April through September collect 4.33. Daylight swings too, by 2 hours 35 minutes between the June and December midpoints. Pick against those two curves and the rest of the trip falls into place.

On this page

• Highs, lows, rain and sea for all twelve monthsThe month-by-month table
• When is the best month to go?May, and the figures behind it
• Sea temperature by monthFrom 76.0°F in March to 80.7°F in October
• When is Honolulu quietest?Mid-September to early December, minus Thanksgiving
• Which month to avoidMarch, and who it hurts
• Is April, May, September or October worth it?What the shoulder costs in daylight

Short version: May for the best balance of heat, rain and water, October for the warmest sea of the year at 80.7°F, March for the month to work around. Every one of the twelve months averages a daytime high above 80°F, so nothing here is a write-off, only better and worse odds on rain.

Honolulu weather month by month: highs, lows, rain and sea

The year splits in two along the rain line, not the thermometer. November through March each take at least 1.84 inches, while none of the six months from April to September reaches a full inch, June bottoming out at 0.50. Temperature barely participates in the argument: 8.3°F stands between August’s 88.8°F and the 80.5°F that January and February share.

March into April is the sharpest turn on the calendar: rain falls from 2.36 inches to 0.77, and wet days from 3.1 to 1.9, in one month. Autumn turns back the other way between September (0.88 inch, 2.2 wet days) and November (2.25 inches, 2.9 wet days), with October as the step in between at 1.51. Nothing in the air temperature announces either switch, since April’s average high of 83.1°F sits only 1.9°F above March’s.

August is the hardest month for anyone who plans to be outdoors and upright. Its 88.8°F average high is the year’s ceiling, and the lows do the real damage at 75.6°F, so the night gives back almost nothing. Walkers on the Diamond Head trail and anyone crossing Waikiki at midday feel that far more than the month’s 0.84 inch of rain. For swimmers, the same August is one of the better months of the twelve, with the sea at 79.6°F.

Every figure here is measured at Honolulu International Airport, on the leeward south shore of Oahu, under NOAA’s 1991-2020 normals. The windward side and the mountains behind it take several times the rain, and this gauge does not see it, so a soaked morning above Manoa can sit alongside a dry day in the table. A wet day means 0.10 inch or more, the American threshold. The second count, an inch or more in a day, peaks in March at 0.7 day per average year, the highest of the twelve.

When is the best time to visit Honolulu?

For the ordinary traveler with a week to spend, the answer is May. The month averages 84.8°F by day and 71.5°F at night, takes 0.82 inch of rain in total across 1.6 days wet enough to register 0.10 inch, and holds the sea at 77.0°F. Mid-May also gives 13 hours 12 minutes of daylight, within sixteen minutes of the longest day of the year.

June beats it on paper for dryness, 0.50 inch against 0.82, and warms the water by 1.4°F. It also runs 2.1°F hotter by day at 86.9°F, and it opens the mainland summer vacation, which no weather figure shows. April makes the other case with less total rain than May, 0.77 inch, but it records more wet days, 1.9 against 1.6, and its water sits at 76.7°F, just 0.7°F above the annual floor of 76.0°F in March.

One caution before you lock May in: these are thirty-year normals, and a single May can deliver the whole month’s 0.82 inch in one afternoon. Watch a real forecast inside ten days. If your dates are still open and Honolulu is one candidate among several, our month-by-month planner puts the same window side by side with everywhere else that is warm then, and the destination index holds the rest.

When can you swim in Honolulu? Sea temperature month by month

No month closes the water here. The coolest average is March at 76.0°F, the warmest is October at 80.7°F, and 4.7°F covers the entire year. If your comfort line is 79°F, five months clear it: July at 79.3, August at 79.6, September at 80.5, October at 80.7 and November at 79.0. The remaining seven land between 76.0 and 78.4°F, warm enough for a long swim and cool enough to notice for the first ninety seconds.

Read those sea figures for what they are. Each is a mean of daily maxima rather than a 24-hour average, drawn from the Open-Meteo marine model over 2015-2024, which is a different source and a different decade from the air normals above. October’s 80.7°F is therefore a warm-afternoon number, and a 7 a.m. swim runs a shade cooler. The model also reads open water off the shore, not any one beach.

When is Honolulu quietest?

The quiet stretches are set by the mainland calendar, not by local weather. The longest runs from mid-September, once school is back, to the first week of December, with Thanksgiving week cut out of it. A second gap opens from mid-January through early March, after the holidays and before spring break. A third and shorter one sits in late April and early May, between spring break and the start of summer vacation.

September and October are the best-paid of those gaps. They hold the warmest water of the year, 80.5°F and 80.7°F, with average highs of 88.4 and 86.9°F and rain still at 0.88 and 1.51 inches. With school in session on the mainland, the sand at Waikiki and the trailhead queues thin out through October and November right up to Thanksgiving week.

The January-to-March gap charges for itself in water and rain. February and March hold 76.1 and 76.0°F, the two coolest readings of the twelve, and take 1.94 and 2.36 inches. Mid-November costs daylight instead: 11 hours 9 minutes on the 15th, which is 2 hours 19 minutes short of the June figure, with the light gone well before dinner.

Which month should you avoid in Honolulu?

March is the month to avoid if the trip is built around the water. It is the wettest of the twelve at 2.36 inches, it records 0.7 day at an inch or more, the highest such count of the year, and its sea runs at 76.0°F, the annual floor. For a conference week, a family visit or a city stay, none of that lands very hard, since the average high is still 81.2°F and the lows hold at 68.1°F.

March redeems itself on light and on the shape of its rain. The 15th carries 12 hours 4 minutes of daylight, 1 hour 11 minutes more than mid-December, and the sun is back over the horizon before 6:37 a.m. local. Only 3.1 days in an average March register even 0.10 inch, which leaves roughly twenty-eight days that do not, and that is the difference between a wet month and a gray one.

Is the shoulder season worth it in Honolulu?

The shoulders are April-May and September-October. Measured against July, the summer benchmark at 88.1°F and 0.52 inch, May runs 3.3°F cooler by day at 84.8°F and takes 0.30 inch more rain. October runs 1.2°F cooler at 86.9°F and takes 0.99 inch more, at 1.51 inches. Those are the whole penalties, and neither is large.

What the shoulder hands you back is water and dry ground. October’s 80.7°F is the warmest sea reading of the year, 1.4°F above July’s 79.3°F, which is the one thing high summer cannot match. At the other end, May’s 1.6 wet days come in lower than every month from September through April, and its 71.5°F nights sit 3.6°F below July’s 75.1°F, which matters in any room without strong air conditioning.

Daylight is the bill. October 15 gives 11 hours 41 minutes against July 15’s 13 hours 20, a loss of 1 hour 39 minutes, and sunset moves from 7:17 p.m. in mid-July to 6:07 p.m. in mid-October. April is gentler on that count, 12 hours 42 minutes on the 15th, still 38 minutes short of July, but it pays in cooler water at 76.7°F.

Take the shoulder. October’s extra inch of rain against July arrives across 2.6 days out of 31, and what it buys, an 80.7°F sea, is the warmest figure Honolulu records all year. If long evenings outrank water temperature for you, take May instead and accept its 0.82 inch and its 77.0°F.

The last word

Book May if the trip is a beach week and stop optimizing: 84.8°F, 0.82 inch, water at 77.0°F. Book the first half of October if the swimming decides everything, and eat early, because the sun is down by 6:07 p.m. One figure that has not been in play yet: January records the most wet days of any month, 3.3 at 0.10 inch or more, even though March takes more rain in total, so January’s water arrives in more visits and smaller ones. And check a windward forecast separately, since the airport gauge does not speak for the other side of Oahu.

Sources & data for this guide

• Monthly air normals, highs, lows, precipitation totals and wet-day counts · NOAA NCEI monthly normals 1991-2020, station USW00022521, Honolulu International Airport · checked Sep 15, 2026
• Gauge location and its leeward-shore limitation (the windward side and the mountains take several times the rain) · NOAA NCEI station metadata · checked Sep 15, 2026
• Sea surface figures, stated as a mean of daily maxima · Open-Meteo Marine API, 2015-2024 average, a different source and period from the air normals · checked Sep 15, 2026
• Daylight lengths, sunrise and sunset on the 15th of each month, converted from UTC to local time · sunrise-sunset.org · checked Sep 15, 2026
• Quiet-season windows are editorial, keyed to the US school and holiday calendar rather than to any price series · we hold no price data for Honolulu and make no cheapest-month claim
• Crowd and comfort judgments are editorial. Normals describe thirty-year averages, not the month you will get · check a forecast inside ten days of travel.