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September Weather in Isa, Japan

Last updated: August 23, 2025

In Isa, Japan, the average temperature in September hovers around 25°C (77°F), creating a comfortable climate for visitors. Expect temperatures to range from a cool 14°C (58°F) to a warm 34°C (94°F). However, be prepared for occasional showers, as the region receives a total precipitation of 259 mm (10.2 in) spread over 18 days during the month. You'll also find the air quite humid, with an average humidity level of 80%, adding a touch of tropical ambiance to your experience.

September Temperature in Isa

In September in Isa, the average temperature is a pleasant 25°C (77°F). Maximums can reach a hot 34°C (94°F), while minimums can dip to a cool 14°C (58°F). This makes it an ideal time for travelers seeking a comfortable climate for outdoor activities and exploration.

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

The chart illustrates September temperature patterns in Isa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Isa, September typically has an average temperature of 25°C (77°F), with highs reaching up to 34°C (94°F) and lows dropping to around 14°C (58°F).
JanFebMarAprMayJunJulAugSepOctNovDec454654606873808277685748
Data source: Temperature data for Isa 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 Isa

In Isa in September, the precipitation amount is 259 mm (10.2 in) over the course of 18 days.

September Precipitation Trends in Isa

The chart displays monthly precipitation patterns in Isa, 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 Isa, September typically receives around 259 mm (10.2 inches) of precipitation spread over approximately 18 days.
JanFebMarAprMayJunJulAugSepOctNovDec6111016215926138648323425914110294
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Isa

In Isa in September humidity is 80%. With an average temperature of 25°C (77°F), this humidity feels like traveling through a warm, tropical rainforest where the air is thick and steamy, making even the simplest stroll feel like a workout.

September Average Humidity in Isa

This chart illustrates the average monthly humidity levels in Isa, 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 Isa is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec72%68%72%79%83%86%90%85%80%78%76%75%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Isa

In Isa in September, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Isa.

Maximum UV Index Levels in Isa for September

The chart shows the monthly maximum UV Index (UVI) for Isa 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 Isa typically reaches 11, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec569111212121311864
Data source: Isa 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.

How September Weather in Isa Compares to Other Months

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

This table compares monthly weather conditions in Isa, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather7°C (45°F)61 mm (2.4 inches)72%moderate
February Weather8°C (47°F)110 mm (4.3 inches)68%high
March Weather12°C (54°F)162 mm (6.4 inches)72%very high
April Weather16°C (61°F)159 mm (6.3 inches)79%extreme
May Weather20°C (68°F)261 mm (10.3 inches)83%extreme
June Weather23°C (74°F)386 mm (15.2 inches)86%extreme
July Weather26°C (80°F)483 mm (19.0 inches)90%extreme
August Weather28°C (82°F)234 mm (9.2 inches)85%extreme
September Weather25°C (77°F)259 mm (10.2 inches)80%extreme
October Weather20°C (69°F)141 mm (5.6 inches)78%very high
November Weather14°C (57°F)102 mm (4.0 inches)76%high
December Weather9°C (48°F)94 mm (3.7 inches)74%moderate

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