September Weather in Seiyo, Japan

Last updated: August 23, 2025

In September, the average temperature in Seiyo, Japan is a pleasant 23°C (74°F). Expect a range from a cool 12°C (54°F) to a warm 33°C (92°F), making it a month of varied weather. Be prepared for 229 mm (9.0 in) of precipitation spread over about 16 days, contributing to an average humidity of 85%. Stay hydrated and enjoy the lush landscapes!

September Temperature in Seiyo

In September in Seiyo, the average temperature is 23°C (74°F). Maximum can reach 33°C (92°F) and minimum can be as low as 12°C (54°F). It's a great time to visit Seiyo for pleasant weather and outdoor activities.

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

The chart illustrates September temperature patterns in Seiyo, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Seiyo, September typically has an average temperature of 23°C (74°F), with highs reaching up to 33°C (92°F) and lows dropping to around 12°C (54°F).

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

September Precipitation in Seiyo

In Seiyo in September, the precipitation amount is 229 mm (9.0 in) over a span of 16 days.

September Precipitation Trends in Seiyo

The chart displays monthly precipitation patterns in Seiyo, 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 Seiyo, September typically receives around 229 mm (9.0 inches) of precipitation spread over approximately 16 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 Seiyo

In Seiyo in September humidity is 85%. With an average temperature of 23°C (74°F), this humidity feels like a thick, steamy blanket wrapping around you, making outdoor activities draining and sweaty, and leaving you longing for a cool breeze or a refreshing drink to ease the discomfort while traveling.

September Average Humidity in Seiyo

This chart illustrates the average monthly humidity levels in Seiyo, 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 Seiyo is approximately 85%, 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 Seiyo

In Seiyo 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 Seiyo.

Maximum UV Index Levels in Seiyo for September

The chart shows the monthly maximum UV Index (UVI) for Seiyo 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 Seiyo typically reaches 11, which falls under the extreme exposure category.

Data source: Seiyo 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 Seiyo Compares to Other Months

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

This table compares monthly weather conditions in Seiyo, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	4°C (40°F)	60 mm (2.4 inches)	74%	moderate
February Weather	5°C (41°F)	97 mm (3.8 inches)	70%	high
March Weather	9°C (49°F)	140 mm (5.5 inches)	70%	very high
April Weather	14°C (57°F)	140 mm (5.5 inches)	76%	very high
May Weather	18°C (65°F)	174 mm (6.8 inches)	82%	extreme
June Weather	22°C (71°F)	236 mm (9.3 inches)	86%	extreme
July Weather	25°C (78°F)	409 mm (16.1 inches)	91%	extreme
August Weather	27°C (80°F)	219 mm (8.6 inches)	88%	extreme
September Weather	23°C (74°F)	229 mm (9.0 inches)	85%	extreme
October Weather	18°C (64°F)	213 mm (8.4 inches)	82%	very high
November Weather	11°C (52°F)	62 mm (2.4 inches)	79%	high
December Weather	6°C (43°F)	69 mm (2.7 inches)	77%	moderate