SeasonMapJacó weather in September
Costa Rica
September in Jacó: sweltering, soaked, with clean air — a gamble, with 30 rainy days.
#11 of 12 months in Jacó · #1177 of 1383 destinations to visit in September · comfort 56/100 (tier D)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Jacó in September
No notes yet. Open Jacó on the map to add the first one.
Jacó climate normals — September
| Daytime high | 28°C / 82°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 24°C / 76°F | |
| Feels like (high) | 34°C / 93°F | |
| Sea temperature | 30°C / 86°F | ♨️ bath-warm |
| Rainfall | 720 mm / 28.3 in | ⛈ soaked |
| Rainy days | 30 days | |
| Humidity | 89% | 💦 very humid |
| Dew point | 24°C / 75°F | |
| Sunshine | 7.6 h/day | |
| Daylight | 12.2 h | |
| Wind | 9 km/h / 6 mph | |
| Air quality (US AQI) | 26 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Jacó 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.
Quietschool holidays in 2 of the markets that fill it, one of its worst months for weather(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Jacó'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).
Toughest weatherJacó's weather peaks January–March, best around February.
Best weatherFair weatherToughest weather
What's on in Jacó in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
South swell season
1 Apr – 31 Oct · usuallySurf seasonThe southern-hemisphere swells arrive through the middle of the year. Playa Hermosa a few minutes down the coast is the serious wave and holds national contests; Jaco's own beach is where people learn.
- Season
Green season
1 May – 30 Nov · usuallyMonsoonMornings stay clear and the rain comes after lunch, hard and short. Rates drop by a third, the hills opposite turn over, and September and October are the two months that genuinely stay grey.
- Nature
Humpback whales
15 Jul – 15 Nov · usuallyWhale seasonSouthern-hemisphere humpbacks calve along this coast from July into November, which with the northern group arriving December to March gives Costa Rica one of the longest whale seasons anywhere.
- Nature
Olive ridley nesting
15 Aug – 15 Dec · usuallyTurtle nestingOlive ridleys nest on Playa Hermosa from August, heaviest through September and October, and the hatchery releases at dusk. The beach is patrolled at night and you go with the project or not at all.
- Season
Wet season
MonsoonRisk30 rainy days and about 720 mm in the month — the real kind of rainy season, not afternoon showers.
from the climate normals
Nearby, and something's on
Within 300 km of Jacó — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Jacó?
Jacó in September — FAQ
- Is September a good time to visit Jacó?
- September in Jacó: sweltering, soaked, with clean air — a gamble, with 30 rainy days. It ranks #11 of 12 months for Jacó on SeasonMap's comfort score (56/100).
- What is the weather like in Jacó in September?
- In September, Jacó averages a daily high of 27.7°C and a low of 24.3°C, with about 719.5 mm of rain over roughly 30 rainy days.
- What is the air quality in Jacó in September?
- Jacó has a mean US Air Quality Index of about 26 in September.
Other months in Jacó
Compare Jacó in September
Warmer or cooler than Jacó in September
Similar destinations in Central America — September
Within 300 km: Nosara's Arribada at Ostional around 1 Jul – 31 Dec, and Tortuguero's Green turtle nesting on 1 Jul – 31 Oct.