Atenas Weather in September
With daytime temperatures of 27°C (81°F) and nighttime lows of 19°C (66°F), September in Atenas brings high temperatures during the day. Do keep in mind that September is part of the rainy season, with frequent and often heavy rainfall.
Rainfall in Atenas in September
As part of the rainy season, Atenas sees around 23 days of rain in September, with an average of 482 mm (19 in). Rainy season showers here are typically intense, often clearing quickly but coming down hard while they last.
Temperature in Atenas in September
Daytime highs in Atenas in September reach 27°C (81°F), with nights around 19°C (66°F). The days can feel warmer than the evenings, so packing for both parts of the day is a good idea. With overnight lows of 19°C (66°F), evenings can feel noticeably cooler than the daytime. An extra layer is a good idea, though the cool air makes for a good night's sleep.
Sunshine in Atenas in September
The area experiences a moderate amount of sunshine, with approximately 147 hours of sunlight expected. Even though this month is part of the rainy season, you could still see the sun every now and then.September in Atenas 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.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Costa Rica, check out our Atenas's climate page.
Atenas Temperature in September
Min Temperature
19°C (66°F)
Max Temperature
27°C (81°F)
Chance of Rain
77%
Precipitation
482 mm (19 in)
Rainy days
23 days
Humidity
86% *
Sunshine
147 hours *
Percentage Sunshine
*
Daily Historical Temperatures
44-year average (1976-2025)
Based on our historical records, temperatures in Atenas typically stay consistent throughout September, with daily highs averaging around 27°C (81°F). Nights are pleasant, with lows around 19°C (66°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 for Atenas in September
Browse day-by-day weather records for Atenas spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Atenas historical weather extremes in September
Based on weather observations in Atenas between 1996 and 2025, these are the recorded extremes during September.
- The hottest September day on record in Atenas reached 32°C (90°F) (September 7, 2009).
- On September 29, 2010, Atenas saw its coldest September day with temperatures maxing out at 21°C (70°F).
- Nighttime temperatures dropped to 13°C (55°F) on September 29, 2010, marking the coldest September night on record.
- The heaviest September precipitation occurred on September 27, 2019, when 168 mm (6.6 in) of precipitation fell.
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
What to Wear in Atenas in September
Warm weather calls for comfortable, breathable clothing in September. Cotton t-shirts, shorts, light dresses, and sandals are perfect. You might still want a light layer for evenings or air-conditioned places (for example buses). 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 Atenas in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Costa Rica, check out our Atenas's climate page.
Temperature Rainfall Sunshine Humidity
See the full Atenas climate overview or explore weather in Costa Rica.
