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September Weather in Niihama, Japan

Last updated: August 23, 2025

In September, the average temperature in Niihama, Japan hovers around 24°C (75°F), with a comfortable minimum of 17°C (62°F) and occasional peaks reaching 32°C (90°F). Expect 237 mm (9.3 in) of precipitation spread over 17 days, contributing to an average humidity of 85%. Embrace the warm, tropical vibe while staying prepared for those refreshing showers!

September Temperature in Niihama

In September in Niihama, the average temperature is 24°C (75°F). Maximums can reach 32°C (90°F), and minimums can be as low as 17°C (62°F). This makes it an ideal time for traveling, as the weather is pleasantly warm, perfect for outdoor activities and exploration.

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

The chart illustrates September temperature patterns in Niihama, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Niihama, September typically has an average temperature of 24°C (75°F), with highs reaching up to 32°C (90°F) and lows dropping to around 17°C (62°F).
JanFebMarAprMayJunJulAugSepOctNovDec424249566571788175665546
Data source: Temperature data for Niihama 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 Niihama

In Niihama in September, the total precipitation amount is 237 mm (9.3 in) spread over a period of 17 days.

September Precipitation Trends in Niihama

The chart displays monthly precipitation patterns in Niihama, 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 Niihama, September typically receives around 237 mm (9.3 inches) of precipitation spread over approximately 17 days.
JanFebMarAprMayJunJulAugSepOctNovDec65851291421481993571812372536980
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Niihama

In Niihama in September humidity is 85%. With an average temperature of 24°C (75°F), this humidity feels like walking through a warm, heavy blanket, making travel feel sluggish and draining as you navigate through the thick, muggy air.

September Average Humidity in Niihama

This chart illustrates the average monthly humidity levels in Niihama, 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 Niihama is approximately 85%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec74%70%70%76%83%86%91%88%85%82%79%77%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Niihama

In Niihama in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Niihama.

Maximum UV Index Levels in Niihama for September

The chart shows the monthly maximum UV Index (UVI) for Niihama 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 Niihama typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec468101111121210764
Data source: Niihama 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 Niihama Compares to Other Months

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

This table compares monthly weather conditions in Niihama, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (42°F)65 mm (2.6 inches)74%moderate
February Weather6°C (43°F)85 mm (3.4 inches)70%high
March Weather9°C (49°F)129 mm (5.1 inches)70%very high
April Weather13°C (57°F)142 mm (5.6 inches)76%very high
May Weather18°C (65°F)148 mm (5.8 inches)82%extreme
June Weather22°C (71°F)199 mm (7.8 inches)86%extreme
July Weather26°C (79°F)357 mm (14.1 inches)91%extreme
August Weather27°C (82°F)181 mm (7.1 inches)88%extreme
September Weather24°C (75°F)237 mm (9.3 inches)85%very high
October Weather19°C (66°F)253 mm (10.0 inches)82%high
November Weather13°C (56°F)69 mm (2.7 inches)79%high
December Weather8°C (46°F)80 mm (3.1 inches)77%moderate

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