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September Weather in Shiojiri, Japan

Last updated: August 23, 2025

In September, the average temperature in Shiojiri, Japan hovers around 19°C (66°F), with minimums dipping to 6°C (42°F) and maximums reaching up to 30°C (86°F). Expect about 171 mm (6.7 in) of precipitation over 16 days, while the air maintains a high average humidity of 86%.

September Temperature in Shiojiri

In September in Shiojiri, the average temperature is 19°C (66°F), with maximums reaching 30°C (86°F) and minimums dropping to as low as 6°C (42°F). This makes Shiojiri a pleasant destination for travelers looking to enjoy mild weather and various outdoor activities.

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

The chart illustrates September temperature patterns in Shiojiri, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Shiojiri, September typically has an average temperature of 19°C (66°F), with highs reaching up to 30°C (86°F) and lows dropping to around 6°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec293040485864727466564434
Data source: Temperature data for Shiojiri 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 Shiojiri

In Shiojiri in September, the precipitation amount is 171 mm (6.7 in) over a span of 16 days.

September Precipitation Trends in Shiojiri

The chart displays monthly precipitation patterns in Shiojiri, 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 Shiojiri, September typically receives around 171 mm (6.7 inches) of precipitation spread over approximately 16 days.
JanFebMarAprMayJunJulAugSepOctNovDec75811411441551492891511712376684
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Shiojiri

In Shiojiri in September, humidity is 86%. With an average temperature of 19°C (66°F), this humidity feels like a warm blanket enveloping you, making travel slightly uncomfortable as the air feels heavy and sticking to your skin.

September Average Humidity in Shiojiri

This chart illustrates the average monthly humidity levels in Shiojiri, 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 Shiojiri is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%74%70%74%82%88%93%90%86%83%80%78%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Shiojiri

In Shiojiri 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 Shiojiri.

Maximum UV Index Levels in Shiojiri for September

The chart shows the monthly maximum UV Index (UVI) for Shiojiri 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 Shiojiri typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec469101111121210754
Data source: Shiojiri 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 Shiojiri Compares to Other Months

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

This table compares monthly weather conditions in Shiojiri, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)75 mm (3.0 inches)76%moderate
February Weather-1°C (30°F)80 mm (3.2 inches)74%high
March Weather4°C (40°F)141 mm (5.6 inches)70%very high
April Weather9°C (48°F)143 mm (5.6 inches)74%very high
May Weather15°C (58°F)155 mm (6.1 inches)81%extreme
June Weather18°C (65°F)149 mm (5.8 inches)88%extreme
July Weather22°C (72°F)289 mm (11.4 inches)93%extreme
August Weather23°C (74°F)151 mm (5.9 inches)90%extreme
September Weather19°C (66°F)171 mm (6.7 inches)86%very high
October Weather13°C (56°F)237 mm (9.3 inches)83%high
November Weather7°C (44°F)66 mm (2.6 inches)80%moderate
December Weather1°C (34°F)84 mm (3.3 inches)78%moderate

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