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San Juan Weather in September
September in San Juan sees daytime temperatures around 23°C (73°F) and lows of 8°C (46°F) at night. The excellent weather makes it a good time to visit.
Rainfall in San Juan in September
The climate data from previous years indicates about 2 days of rain, averaging 24 mm (0.9 in) for the month. The rain this month typically falls in concentrated bursts rather than all-day showers. Expect a few heavier spells rather than constant grey skies.
Temperature in San Juan in September
September tends to be one of the excellent months in San Juan, with 23°C (73°F) in the afternoon and 8°C (46°F) overnight. Conditions stay fairly consistent through the month, making it easier to plan what to wear. Nights fall to 8°C (46°F), which is cold enough to feel it indoors too. A good thick duvet makes all the difference for a comfortable night's sleep.
Sunshine in San Juan in September
Expect sunny days throughout the month, with an estimated 263 hours of sunshine. This makes it a pleasant time to visit San Juan.If you're inclined towards comfortable temperatures and drier conditions, September is a good time to visit San Juan.
San Juan Temperature in September
Min Temperature
8°C (46°F)
Max Temperature
23°C (73°F)
Chance of Rain
8%
Precipitation
24 mm (0.9 in)
Rainy days
2 days
Humidity
42%
Sunshine
263 hours
Percentage Sunshine
74%
San Juan Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in San Juan - and find the best time to visit.
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in San Juan typically rise from around 21°C (70°F) at the start of September to approximately 25°C (77°F) by the end. Nights are cold, with lows typically ranging from 5°C (41°F) to 10°C (50°F).
Average temperatures in September
Historical weather records for San Juan in September
Browse day-by-day weather records for San Juan spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
San Juan historical weather extremes in September
Based on 50 years of weather observations (1976-2026), these are the most extreme conditions recorded in San Juan.
- On September 22, 2018, temperatures climbed to 38°C (100°F), marking the warmest September day on record.
- The coldest night in September in San Juan was on September 7, 2026, with a minimum of -3°C (27°F).
Best Places in Argentina in September
Find out more about the weather in Argentina and which places have the best travel conditions in this month. See all of Argentina in September →
perfect weather
pleasant
tolerable
unpleasant
poor
Perfect weather is subjective. On this map perfect weather has been defined with temperatures between 20°C (68°F) and 29°C (84°F) and not too much precipitation (less than 90 mm (3.5 in) a month).
What to Wear in San Juan in September
Comfortable temperatures call for an easy wardrobe in September. Pack summer basics like t-shirts and shorts, but include a light jacket for cooler moments. A pair of comfortable walking shoes is essential. Light rain is possible, so consider bringing a small umbrella or rain jacket. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.
What To Do in San Juan in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
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Swimming10/10 -
Cycling10/10 -
Walking10/10 -
Barbeque9/10 -
Camping5/10 -
Outdoor sports10/10
San Juan 3-Day Forecast
More climate data for San Juan
Temperature Rainfall Sunshine Humidity
See the full San Juan climate overview or explore weather in Argentina.
Popular in September
Where to go in September - average daytime high across popular destinations.
Córdoba
23°C (73°F) Salta21°C (70°F) Mendoza20°C (68°F) Buenos Aires
20°C (68°F) Mar del Plata16°C (61°F) San Martín de los Andes
8°C (46°F) San Carlos de Bariloche8°C (46°F) Bucket list
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