San Carlos Weather in September
What's the weather like in San Carlos (Río San Juan) in September 2025?
The climate in San Carlos during September can be summarized as hot, humid and very wet.
September is in the fall / autumn in San Carlos and is typically the 3rd coldest month of the year. Daytime maximum temperatures average around a steamy 30°C (85°F), whilst at night 23°C (72°F) is normal.
| Daytime temperature | 29.6°C 85.2°F |
|---|---|
| Nightly temperature | 22.5°C 72.4°F |
| Average temperature | 26°C 78.8°F |
| Daily sunshine | 6.2 hrs |
| Avg rainfall | 246 mm 9.7 ins |
| Rainy days | 23 days |
| Sea temperature | 28.9°C 84°F |
| Humidity | 85% |
| Windspeed | 7.6kph 5 mph |
On average September is the 5th wettest month of the year in San Carlos with around 246mm 9.7 inches of rain making it a very wet time to visit. This rainfall is typically spread over 23 days, although this may vary considerably.
On the flip side this corresponds to an average of 6.2 hours of sunshine per day.
September temperatures in San Carlos
September rainfall
September hourly sunshine
The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in San Carlos in September 2025.
Other monthly averages
Best places to visit in September
San Carlos weather stats
| Hottest month: | April | 32.2°C 90°F |
|---|---|---|
| Driest month: | March | 25mm 1ins |
| Sunniest month: | May | 7.7hrs |
| Coldest month: | November | 29°C 84.2°F |
| Wettest month: | July | 323mm 12.7ins |
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