September Weather in Arenal, Peru

Last updated: August 27, 2025

September in Arenal, Peru, offers a delightful escape for travelers, showcasing a maximum temperature of 28°C (83°F) and a comfortable average of 20°C (69°F). With temperatures dipping to a minimum of 15°C (60°F), evenings are pleasantly cool. Notably, this month boasts an impressive precipitation total of just 1 mm (0.1 in) and zero rainy days, allowing for uninterrupted enjoyment of outdoor activities. The climate, coupled with a humidity level of 75%, creates a lush environment that truly highlights the natural beauty of this region. Whether you're exploring the vibrant ecosystems or relaxing amidst stunning scenery, September in Arenal is nothing short of remarkable.

September Temperature in Arenal

In September, Arenal, Peru experiences a gentle transition into milder temperatures, with a minimum of 15°C (60°F) and a comfortable average of 20°C (69°F). As the month progresses, the maximum temperature reaches 28°C (83°F), indicating a pleasant blend of warmth and refreshing breezes. This period marks an interesting shift from the cooler, wetter August, displaying a gradual rise in temperatures while maintaining an overall comfortable climate. Ideal for exploring the lush scenery, September's mild weather fosters an inviting atmosphere, perfect for engaging in outdoor adventures and enjoying the breathtaking beauty of Arenal.

September Weather in Arenal: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Arenal, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Arenal, September typically has an average temperature of {2}°C ({3}°F), with highs reaching up to {4}°C ({5}°F) and lows dropping to around {6}°C ({7}°F).
JanFebMarAprMayJunJulAugSepOctNovDec778080777471696868697074
Data source: Temperature data for Arenal generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Arenal

September in Arenal, Peru, marks a transition into a notably drier period, featuring a mere 1 mm (0.1 in) of precipitation, mirroring the exceptionally low rainfall of the previous two months. This month experiences zero precipitation days, signifying a stark contrast to the wet season that typically grips the region earlier in the year. The rainfall trend leading into September reveals a substantial decline from the 93 mm (3.7 in) recorded in March, suggesting a shift towards more placid weather patterns. As the year progresses, Arenal continues to embrace the dry spell, hinting at a clear shift in climate dynamics as it heads into October and beyond.

September Precipitation Trends in Arenal

The chart displays monthly precipitation patterns in Arenal, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Arenal, September typically receives around {2} mm ({3} inches) of precipitation spread over approximately {4} days.
JanFebMarAprMayJunJulAugSepOctNovDec11429319622114516
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Arenal

In September, humidity levels in Arenal, Peru settle at a comfortable 75%, marking a slight increase from the drier months of July and August, which recorded 71% each. This transition reflects the region's gradual return to its lush, verdant climate as it approaches the end of the dry season. Overall, the humidity this month indicates a consistent pattern where early fall offers a more moderate level compared to the intense moisture seen earlier in the year, particularly in January and May, both at an impressive 89%. With October following closely at 77%, September serves as a gentle bridge between the humid extremes, making it an ideal time for visitors to experience Arenal’s vibrant ecosystem without the oppressive wetness of peak season.

September Average Humidity in Arenal

This chart illustrates the average monthly humidity levels in Arenal, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Arenal is approximately {2}%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%87%87%86%89%84%71%71%75%77%79%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Arenal

In September, visitors to Arenal, Peru, will experience a UV Index of 13, categorized as extreme, indicating a consistent need for sun protection. This month follows a trend seen throughout the year, where the UV Index hovers between 11 and 16 from January to August, with only slight fluctuations. With a burn time of just 10 minutes, the intensity of the sun remains a key concern, urging outdoor enthusiasts to remain vigilant against overexposure. As the month rolls into the more intense sun months ahead, it’s crucial to stay informed about the ever-present risks associated with high UV levels. For more detailed information on UV exposure, check out Arenal UV Index.

Maximum UV Index Levels in Arenal for September

The chart shows the monthly maximum UV Index (UVI) for Arenal in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Arenal typically reaches {2}, which falls under the {3} exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec141516151311111213131313
Data source: Arenal September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

September Sunshine in Arenal

September in Arenal, Peru, brings a delightful blend of warmth and sunshine, with 323 hours of glorious daylight gracing the skies. As the rainy season nears its end, the month maintains a vibrant profile, nestled comfortably between the sunniest days of May and the cooler, cloudier periods of October. This pattern highlights a steady increase in sunlight leading up to September, peaking during the mid-year months. With only a slight dip from the bustling August warmth, September continues to invite outdoor adventures amid picturesque landscapes, making it an excellent time for exploration and appreciation of Arenal's natural beauty. Enjoy the sun-kissed days before the landscape transforms for the upcoming months!

Monthly Sunshine Duration in Arenal: September Highlighted

The September sunshine duration represents the total number of hours Arenal experiences direct sunlight during the month of September, excluding cloudy or obstructed periods. This chart compares the sunshine duration of September with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec275h302h317h324h334h316h327h332h323h333h326h345h
Data source: Arenal September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Arenal During September

As September unfolds in Arenal, Peru, the likelihood of sunny weather pleasantly stands at 49%, marking a promising point in the year's transition. Following a trend of increasing sunshine, where May boasts a high 63% chance, the arrival of September signifies a gradual tapering off as the region approaches the wetter months. While the probability isn't at its peak, it offers a considerable opportunity for outdoor activities, especially when contrasted with the cooler, cloudier months of October at 35% and November at 30%. Thus, September is a delightful window of opportunity to soak up some sun before the rains return.

Percentage of Sunny Days in September in Arenal

The chart illustrates the percentage of sunny days in Arenal throughout the year, with September highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Arenal experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec31%31%28%40%63%43%56%41%49%36%30%29%
Data source: Arenal September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Arenal in September

In Arenal, Peru, September brings a refreshing return to longer days, offering 12 hours of daylight that align with the first months of the year. Throughout the year, daylight duration remains relatively stable, with consistent 12-hour stretches from January to March and again from October through December. In contrast, the months from April to August experience a slight decrease, settling at 11 hours as the region transitions through the cooler middle of the year. This rhythmic pattern highlights Arenal’s unique tropical climate, where the even distribution of daylight allows for vibrant outdoor activities year-round, making September a particularly inviting month for exploration.

Average Daylight Hours in Arenal for September

The chart illustrates the variation in daylight duration in Arenal throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec12h 21m12h 14m12h 6m11h 58m11h 52m11h 49m11h 51m11h 56m12h 4m12h 12m12h 19m12h 23m
Data source: Arenal daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Arenal

As September rolls into Arenal, Peru, the winds begin to pick up a gentle pace, averaging 3.9 m/s (or 9 mph). This increase marks a shift in the seasonal patterns, as wind speeds gradually rise from the calmer months of earlier in the year, where averages hovered around 3.3-3.7 m/s. Interestingly, September shares this brisk momentum with August, hinting that these early fall days present a refreshing breeze that lingers into the heart of spring. The consistent uptick in wind speed towards the end of the year peaks in October at 4.0 m/s, suggesting that nature is subtly gearing up for the more dynamic weather ahead. Overall, September stands as a delightful crossroads, offering not just gentle breezes but also a hint of the lively winds to come.

Average September Wind Speed in Arenal

The chart displays monthly wind speed patterns in Arenal, with values for each month shown alongside September's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how September's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec3.33.42.73.43.63.73.63.93.9 m/s4.03.73.6
Data source: Arenal September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Arenal Compares to Other Months

Weather in Arenal varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Arenal, focusing on differences in temperature, rainfall, humidity, and UV levels.

September and January exhibit notable differences in weather patterns. In September, temperatures range from a mild 15°C (60°F) at night to a warm 28°C (83°F) during the day, with an average of 20°C (69°F). This month is characterized by minimal precipitation, averaging just 1 mm (0.1 in) and experiencing no rainy days, along with a humidity level of 75%. In contrast, January sees a warmer climate with minimum temperatures of 19°C (66°F) and maximums reaching up to 34°C (94°F), averaging 25°C (78°F). This month experiences more rainfall, totaling 10 mm (0.4 in) over three days, and higher humidity at 89%. For more details on January weather, you can check Arenal weather in January.

In September, the weather is mild with temperatures ranging from a minimum of 15°C (60°F) to a maximum of 28°C (83°F), making the average temperature a pleasant 20°C (69°F). With only 1 mm of precipitation over the course of the month and 75% humidity, September offers mostly dry and comfortable days. In contrast, February sees warmer conditions with minimum temperatures of 20°C (68°F) and a maximum of 34°C (94°F), averaging around 26°C (80°F). However, it is also significantly wetter, experiencing about 42 mm of precipitation spread over 6 days and higher humidity at 87%. For more insights, you can explore Arenal weather in February.

In comparing September and March weather, September presents a milder climate with average temperatures ranging from a minimum of 15°C (60°F) to a maximum of 28°C (83°F), along with minimal precipitation (just 1 mm) and no rainy days, resulting in relatively comfortable humidity levels around 75%. In contrast, March experiences significantly warmer temperatures, with a minimum of 21°C (69°F) and a maximum soaring to 35°C (95°F). However, it also brings considerable rainfall, averaging 93 mm over 8 days and a higher humidity of 87%. For more details on March weather specifics, check out Arenal weather in March.

In comparing the weather between September and April, we see notable differences in temperature and precipitation. September has a milder temperature range with minimums of 15°C (60°F) and maximums reaching 28°C (83°F), while April boasts warmer conditions, ranging from a minimum of 18°C (65°F) to a maximum of 34°C (94°F). Additionally, April experiences more significant rainfall, totaling 19 mm (0.8 in) across two days, contrasting sharply with September's dry spells, where precipitation is virtually nonexistent. Humidity levels are also slightly higher in April at 86% compared to September's 75%, making April feel more humid overall. For more details regarding weather specifics, you can check this link: Arenal weather in April.

September typically sees milder temperatures with a minimum of 15°C (60°F) and an average of 20°C (69°F), reaching a maximum of 28°C (83°F). This month is characterized by very low precipitation, averaging only 1 mm (0.1 in) across no rainy days, and a humidity level of 75%. In contrast, May experiences warmer conditions, with a minimum of 16°C (62°F), an average of 23°C (74°F), and maximum temperatures peaking at 32°C (91°F). May also brings slightly higher precipitation levels at 6 mm (0.2 in) over two days, along with increased humidity at 89%. For more details on May weather, check out Arenal weather in May.

September generally offers milder temperatures compared to June, with average highs reaching 28°C (83°F) versus June's warmer 31°C (87°F). The minimum temperatures in September are slightly cooler at 15°C (60°F), whereas June starts a bit higher at 17°C (63°F). Precipitation levels are similar, with both months experiencing minimal rain, but June has a slightly higher average humidity at 84% compared to September's 75%. For more details, you can check out the following link: Arenal weather in June.

In comparing the weather of September and July, both months exhibit quite similar conditions, with average temperatures hovering around 20°C (69°F). September experiences a slightly wider range, with minimum temperatures at 15°C (60°F) and maximums reaching up to 28°C (83°F), while July's temperatures are a bit more consistent, ranging from 16°C (60°F) to a maximum of 27°C (82°F). Notably, both months have negligible precipitation, with only 1 mm (0.1 in) recorded and no rainy days, along with relatively high humidity levels—75% in September compared to 71% in July. For a closer look at July's climate, you can check out Arenal weather in July.

In September, the weather remains quite similar to August, with temperatures showing only slight variations. The minimum temperature is the same at 15°C (60°F), while the average rises slightly to 20°C (69°F) and the maximum increases to 28°C (83°F). Both months experience negligible precipitation, with just 1 mm recorded, and no rainy days. Humidity is a bit higher in September, reaching 75%, compared to August's 71%. For more details, check out Arenal weather in August.

September typically offers mild weather with an average temperature of 20°C (69°F) and a maximum of 28°C (83°F), complemented by low precipitation and moderate humidity at 75%. In contrast, October sees a slight increase in temperatures, with an average of 21°C (70°F) and highs reaching 29°C (85°F). While both months remain mostly dry, October experiences slightly more rainfall at 4 mm, along with a modest rise in humidity to 77%. For more insights, you can check out Arenal weather in October.

September and November showcase mild and pleasant weather, though with some notable differences. In September, temperatures range from a minimum of 15°C (60°F) to a maximum of 28°C (83°F), with an average of 20°C (69°F) and virtually no precipitation, resulting in a dry atmosphere with a humidity level of 75%. By November, the temperatures slightly increase, with minimums around 15°C (59°F) and maximums reaching 30°C (86°F), while the average temperature is 21°C (70°F). November also sees a modest increase in precipitation, totaling 5 mm (0.2 in) over just one day, leading to a slightly more humid environment at 79%. For more specific details on November conditions, you can refer to Arenal weather in November.

In September, the weather tends to be mild and pleasant, with average temperatures around 20°C (69°F) and a comfortable maximum of 28°C (83°F). Humidity levels are moderate at 75%, and the month typically experiences no precipitation, making it an ideal time for outdoor activities. In contrast, December sees a rise in temperatures, with minimums of 17°C (64°F) and average highs reaching 32°C (89°F). However, it also brings increased humidity at 86% and some precipitation, totaling 16 mm over about three days. For more details on the December weather, you can visit Arenal weather in December.

Compare Arenal's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Arenal

September in Arenal presents a delightful climate that stands out from other months, marked by pleasantly warm temperatures and notably dry conditions. With a maximum of 28°C and an average around 20°C, visitors can enjoy comfortable days without the interruption of rain, as the area experiences practically no precipitation. This makes September an ideal time for outdoor activities amid the lush surroundings. The 75% humidity adds a touch of tropical warmth, but it is the lack of rainfall that truly distinguishes this month, enabling bright and sunny adventures. For those looking to explore, September's unique weather offers a wonderful opportunity to experience Arenal's natural beauty without the typical interruptions of the rainy season. To learn more about the climate and what to expect throughout the year, visit Arenal Climate.