Weather in Honolulu in August

A good month. August is a solid month to be in Honolulu. Highs average 28.5 °C, lows 25.5 °C, and rain falls on 10 days — nothing in the month is working against you.

Honolulu barely has seasons. August scores 76 out of 100 against a best of 81 in May — a gap small enough that the month you choose matters far less here than the week you choose.

Rain on 10 days, 1 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 28.5 °C days and 25.5 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: the day barely swings — 3 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest August day reached 30.5 °C and the coldest night fell to 24 °C, and the wettest single day dropped 51 mm — roughly 116% of the month's rain in one day.

This is the volatile part. August rainfall has ranged from 5 mm to 148 mm across the twenty years measured — a 143 mm spread around an average of 44 mm. The average is real but almost no individual August looks like it, so treat the figure as the middle of a wide range rather than a forecast.

Wind sits around 21.8 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity is unremarkable at 74%.

How August sits in the year

Temperatures hold steady either side: 28.1 °C in July, 28.5 here, 28.6 in September. Nothing about the timing within the month matters much.

Daylight in August

August is at or near the longest days of Honolulu's year: 12.9 hours of daylight, losing 0.5 hours across the month. Evenings are the real gain — dinner outdoors still happens in full light.

Sea temperature

The sea sits at about 26.3 °C in August — warm enough to stay in as long as you like. This is the warmest the water gets all year.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

August in Honolulu versus nearby

Honolulu has no close neighbour worth comparing against, so the useful question is how August there compares with August elsewhere. San Francisco in August is a clearly better month — 23.6 °C and rain on 0 days, against 28.5 °C and 10 here. San Jose in August is much the same — 31.6 °C and rain on 0 days, against 28.5 °C and 10 here.

So: August is effectively as good as it gets here — 5 points behind May, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Honolulu

See all twelve months in Honolulu, or where else to go in August.