San José
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San José Weather in September

In San José, September brings high daytime temperatures around 24°C (75°F), with nights cooling to 16°C (61°F). This month falls within the rainy season, so expect frequent rainfall.

Rainfall in San José in September

As part of the rainy season, San José sees around 24 days of rain in September, with an average of 476 mm (19 in). Rain during the rainy season here tends to be intense rather than just persistent drizzle. Expect significant downpours.

Temperature in San José in September

September in San José brings high temperatures, with highs of 24°C (75°F) and nights around 16°C (61°F). Conditions stay fairly consistent through the month, making it easier to plan what to wear. With lows of 16°C (61°F), nights are cool. If you're out after dark, an extra layer will keep you comfortable. The cooler air at night is also great for getting a good rest.

Sunshine in San José in September

The city usually sees around 149 hours of sunlight, indicating a moderately sunny period (despite it being part of rainy season).

September in San José has its charm. However, if you're seeking pleasant, dry and sunny weather, our weather planner can help you explore other destinations in the world.

San José Temperature in September

Min Temperature
16°C (61°F)
Max Temperature
24°C (75°F)
Chance of Rain
79%
Precipitation
476 mm (19 in)
Rainy days
24 days
Humidity
85%
Sunshine
149 hours
Percentage Sunshine

San José Weather by Month

Pick a month to see the average temperature, rainfall and sunshine in San José - and find the best time to visit.

Daily Historical Temperatures

44-year average (1976-2025)

Based on our historical records, temperatures in San José typically stay consistent throughout September, with daily highs averaging around 24°C (75°F). Nights are pleasant, with lows around 18°C (64°F).

Average temperatures in September

Daily Historical Precipitation

44-year average (1976-2025)

Average daily rainfall for each day of the month based on long-term records.

Average precipitation in September

Historical weather records for San José in September

Browse day-by-day weather records for San José spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.

San José historical weather extremes in September

Based on 30 years of weather observations in San José between 1996 and 2026, these are the recorded extremes.

  • The warmest day in September was on September 7, 2009, with a maximum of 34°C (93°F).
  • The coldest September day was on September 29, 2010, with a maximum of 21°C (70°F).
  • The coldest night in September in San José was on September 29, 2010, with a minimum of 14°C (57°F).
  • Peak precipitation in September occurred on September 27, 2019, when 164 mm (6.5 in) of precipitation was measured.

Best Places in Costa Rica in September

Find out more about the weather in Costa Rica and which places have the best travel conditions in this month. See all of Costa Rica 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 José in September

For San José in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. Also bring a poncho, it will rain a lot! Waterproof everything you can. Sunglasses could come in handy during the sunnier parts of your trip.

What To Do in San José in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

  • Swimming
    7/10
  • Camping
    6/10

San José 3-Day Forecast

More climate data for San José

Popular in September

Where to go in September - average daytime high across popular destinations.

Bucket list

Need travel inspiration? Check out our bucket list articles and be inspired.