Costa Rica
Costa Rica in September: weather, sea & travel advice
This month's data profile
Rain shapes the decision
Costa Rica in September is climatically mixed. The average daily high is around 30 °C, and the sea is about 29 °C. With about 26 rainy days it is very wet.
Historical monthly averages, not a weather forecast. Individual days and years can differ substantially.
Rank among 12 monthly averages
52/100 · #8
Warmth
#10
Dryness
#12
Sun
#8
Sea warmth
#6
Published best categories: none
Costa Rica · SeptemberPhoto: Shiva Shenoy from Flower Mound, United States · CC BY 2.0Climate facts
- Average high
- 30 °C
- Average low
- 25 °C
- Sea
- 29 °C
- Rainy days (est.)
- 26 rainy days (est.)
- Sun (est.)
- 6 h/day
- Humidity
- 83 %
Climate evidence with direct month comparison
The highlighted row is the selected month. Precipitation total and rainy days are separate monthly averages.
| Month | Avg high °C | Avg low °C | Rainy days (est.) | Precipitation mm | Sun h/day (est.) | Humidity % | Wind m/s | Sea °C | Score |
|---|---|---|---|---|---|---|---|---|---|
| August | 31 | 25 | 22 | 189 | 6.2 | 80 | 2.1 | 29 | 51 |
| September (selected) | 30 | 25 | 26 | 270 | 6.1 | 83 | 1.9 | 29 | 52 |
| October | 29 | 24 | 25 | 279 | 5.6 | 86 | 2.1 | 28 | 55 |
How do the previous and next months compare?
Baseline: September (52/100)
Positive and negative values show the change from the selected month.
| Score Δ | Average high Δ | Average low Δ | Rainy days Δ | Rain Δ | Sun Δ | Humidity Δ | Wind Δ | Sea Δ | |
|---|---|---|---|---|---|---|---|---|---|
| August | -1 | +0.9 °C | +0.1 °C | -4.1 | -81 mm | +0.1 h | -3.3 % | +0.2 m/s | +0.1 °C |
| October | +3 | -0.9 °C | -0.3 °C | -1.1 | +9.3 mm | -0.5 h | +2.6 % | +0.2 m/s | -0.5 °C |
All twelve months in context
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Useful next decisions
Frequently asked questions
How warm is Costa Rica in September?
The average daily high is around 30 °C, with an average daily low of about 25 °C.
Can you swim in Costa Rica in September?
The sea is about 29 °C (very warm).
Does it rain a lot in Costa Rica in September?
The curated estimate is about 26 rainy days per month, not a directly measured long-term average. Total precipitation averages around 270 mm for the month. A rainy day does not mean all-day rain.
When is the best time to visit Costa Rica?
By the climate score, January, February, March and December are the strongest months for Costa Rica. For a beach trip: January, February, November and December. September is not among them.