Kona weather in September
September in Kona: sweltering, soaked, with clean air — fine if you can take 20 rainy days.
Updated September 2026 · climate normals from ERA5 reanalysis
#9 of 12 months in Kona · #571 of 1413 destinations to visit in September · comfort 83/100 (tier A)
- Days
- 30°C
- Nights
- 24°C
- Wet days
- 20
- Sun
- 11.2 h
- Humidity
- 85%
- Daylight
- 12 h
Traveller notes on Kona in September
Kona forum regulars are consistent about September: it's hot and sticky, and the trade winds that usually cool the coast can break down for stretches, so there's less relief than you'd expect. It's still technically hurricane season, and while a direct hit is rare, the remnants of a passing system can bring heavy surf and a burst of heavy rain even on an otherwise sunny week. That said, several posters described near-perfect two-week stretches with no crowds and easy access to snorkeling spots - it's a gamble, but one that tends to pay off more often than not.
Other months in Kona
March in Kona is the tail of whale season — humpbacks run from about mid-December to late March, thinning as the month goes on, so mid-March is still reliable and the very end of it is not. On rain, the forum's line that March is one of the Big Island's wettest months is about the windward side: on Kona's leeward coast March is one of the drier months, ten rain-days against fourteen through the summer. The variable that is genuinely local is vog — volcanic haze concentrates in the Kailua-Kona area and can bring headaches and eye and lung irritation, more seriously for asthma. The regulars' fix is geographic: drive north a few beaches and it largely clears.
Add your own note from Kona's card on the map.
Kona climate normals — September
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Kona in September
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Quiettravelers describe it as quiet, Summer break in United States
Sourced from traveler notes: “…eral posters described near-perfect two-week stretches with no crowds and easy access to snorkeling spots - it's a gamble, but on…” — BigIslandRegular
Peak crowdsBusyShoulder seasonQuiet
Best months for Kona's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherKona's weather doesn't swing hard through the year — comfort stays fairly steady in every month.
What's on in Kona in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Hazard
Vog from Kīlauea
1 Jan – 31 DecVolcanic activitySulphur haze from the volcano drifts round the south point and settles along this coast, which is why the Kona side gets the hazy afternoons rather than the windward towns. It comes and goes with the eruption and the wind, not with the calendar. Source ↗
- Hazard
Central Pacific hurricane season
1 Jun – 30 NovMost systems that reach Hawaii shear apart before landfall, but the season is real and August and September are the busy weeks. The bigger practical risk on this coast is the surf a distant storm sends onto the boat ramps. Source ↗
- Nature
Kona coffee harvest
1 Sep – 15 Jan · usuallyThe cherry ripens unevenly on the slopes above town, so pickers go through the same trees several times between September and January. Farm tours are worth doing while there is actually fruit on the branch.
Nearby, and something's on
Within 300 km of Kona — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Kona?
Kona in September — FAQ
- Is September a good time to visit Kona?
- September in Kona: sweltering, soaked, with clean air — fine if you can take 20 rainy days. It ranks #9 of 12 months for Kona on SeasonMap's comfort score (83/100).
- What is the weather like in Kona in September?
- In September, Kona averages a daily high of 29.8°C and a low of 24°C, with about 159.7 mm of rain over roughly 20.1 rainy days.
- What is the air quality in Kona in September?
- Kona has a mean US Air Quality Index of about 17 in September.
Within 300 km: Honolulu's Aloha Festivals around 1–30 Sep, and Hilo's Mango and tropical fruit harvest around 1 Jun – 30 Sep.