September Weather in Onna, Japan

Last updated: August 23, 2025

In Onna, Japan, the average temperature in September hovers around 28°C (82°F), with a minimum of 24°C (75°F) and a maximum reaching up to 30°C (86°F). Expect 237 mm (9.3 in) of precipitation spread over 18 days, leading to an average humidity of 82%. This combination makes September a warm and humid time to experience the charm of Onna.

September Temperature in Onna

In September in Onna, the average temperature is 28°C (82°F). The maximum can reach 30°C (86°F), and the minimum can be as low as 24°C (75°F). This pleasant climate makes it an ideal time for outdoor activities and exploring the local attractions.

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

The chart illustrates September temperature patterns in Onna, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Onna, September typically has an average temperature of 28°C (82°F), with highs reaching up to 30°C (86°F) and lows dropping to around 24°C (75°F).

Data source: Temperature data for Onna generated using information from the Copernicus Climate Change Service.

September Precipitation in Onna

In Onna in September, the precipitation amount is 237 mm (9.3 in) over the course of 18 days.

September Precipitation Trends in Onna

The chart displays monthly precipitation patterns in Onna, 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 Onna, September typically receives around 237 mm (9.3 inches) of precipitation spread over approximately 18 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Onna

In Onna in September humidity is 82%. With an average temperature of 28°C (82°F), this humidity feels like walking through a warm, dense blanket, making outdoor activities a challenge and necessitating frequent breaks to stay hydrated.

September Average Humidity in Onna

This chart illustrates the average monthly humidity levels in Onna, 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 Onna is approximately 82%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Onna

In Onna in September, the maximum UV index is 12, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, underscoring the importance of sun protection. For detailed information, you can check the Hourly UV Index in Onna.

Maximum UV Index Levels in Onna for September

The chart shows the monthly maximum UV Index (UVI) for Onna 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 Onna typically reaches 12, which falls under the extreme exposure category.

Data source: Onna 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 Onna Compares to Other Months

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

This table compares monthly weather conditions in Onna, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	18°C (65°F)	99 mm (3.9 inches)	71%	high
February Weather	18°C (65°F)	98 mm (3.9 inches)	71%	very high
March Weather	20°C (68°F)	109 mm (4.3 inches)	76%	extreme
April Weather	21°C (70°F)	146 mm (5.7 inches)	82%	extreme
May Weather	24°C (75°F)	213 mm (8.4 inches)	84%	extreme
June Weather	26°C (80°F)	328 mm (12.9 inches)	86%	extreme
July Weather	28°C (83°F)	180 mm (7.1 inches)	86%	extreme
August Weather	28°C (83°F)	187 mm (7.4 inches)	82%	extreme
September Weather	28°C (82°F)	237 mm (9.3 inches)	82%	extreme
October Weather	26°C (78°F)	149 mm (5.8 inches)	80%	very high
November Weather	23°C (74°F)	106 mm (4.2 inches)	79%	very high
December Weather	20°C (68°F)	162 mm (6.4 inches)	75%	high