Monthly climate guide
San Juan weather in September
Expect warm weather in San Juan in September: afternoons reach about 24°C (74°F), while nights drop to around 7°C (44°F). Around 2 mm of rain falls over the month (very dry), and skies are mostly sunny. Daytime highs are 3°C warmer than August and 3°C cooler than October.
What stands out in September
- Seasonally, September counts as early spring in San Juan — the seasons are reversed south of the equator.
- Just 290 km apart, but San Juan runs about 2°C cooler than La Rioja this month.
- Skies are at their clearest this time of year.
- Evenings cool off sharply: the daily range is around 17°C, so pack a layer.
Avg high
24°C
74°F
Avg low
7°C
44°F
Rainfall
2 mm
very dry
Humidity
33%
relative
Sky
29%
cloud · mostly sunny
San Juan weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 32°C / 89°F | 17°C / 63°F | 24 mm | 41% | 38% |
| February | 30°C / 87°F | 16°C / 61°F | 35 mm | 46% | 37% |
| March | 28°C / 82°F | 14°C / 56°F | 15 mm | 46% | 33% |
| April | 25°C / 76°F | 10°C / 51°F | 6 mm | 48% | 36% |
| May | 21°C / 70°F | 7°C / 44°F | 3 mm | 45% | 44% |
| June | 19°C / 66°F | 4°C / 39°F | 2 mm | 36% | 34% |
| July | 18°C / 65°F | 3°C / 38°F | 2 mm | 36% | 34% |
| August | 21°C / 70°F | 5°C / 40°F | 2 mm | 31% | 29% |
| September | 24°C / 74°F | 7°C / 44°F | 2 mm | 33% | 29% |
| October | 26°C / 79°F | 9°C / 49°F | 5 mm | 34% | 35% |
| November | 29°C / 84°F | 13°C / 55°F | 27 mm | 35% | 32% |
| December | 31°C / 89°F | 16°C / 60°F | 23 mm | 36% | 29% |
What to pack for September
- T-shirts plus a light layer for the evening
- Comfortable trainers or sandals for long walks
- An extra layer — evenings are noticeably cooler than afternoons
- Sunglasses
Is September a good time to visit San Juan?
Compare the months in the chart above to find your ideal window.
Best time to visit San Juan →Other Argentina cities in September
Cite or embed this data
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San Juan weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/argentina/san-juan/september
<a href="https://weathercompare.eu/weather/argentina/san-juan/september">San Juan weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/argentina/san-juan" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="San Juan weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/argentina/san-juan/september">San Juan weather in September</a> – WeatherCompare</p>
San Juan in September: quick answers
Is September a good time to visit San Juan?
September is a reasonable time for San Juan: highs around 24°C and about 2 mm of rain, though not one of the three best months.
How warm is San Juan in September?
Average highs are about 24°C (74°F) and average lows about 7°C (44°F), based on 10 years of daily data.
Does it rain a lot in San Juan in September?
San Juan typically gets around 2 mm of rain in September — very dry.
Figures are long-term averages for the area around San Juan (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.