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September Weather in Yanai, Japan

Last updated: August 23, 2025

In September, the average temperature in Yanai, Japan hovers around 24°C (76°F). Expect a comfortable range with minimum temperatures at 18°C (65°F) and highs reaching up to 31°C (88°F). Be prepared for some rain, as 215 mm (8.5 in) of precipitation may fall over about 13 days. With an average humidity level of 84%, the atmosphere feels quite tropical.

September Temperature in Yanai

In September in Yanai, the average temperature is 24°C (76°F), with maximums reaching 31°C (88°F) and minimums dropping to as low as 18°C (65°F). This mild climate makes Yanai an ideal destination for travelers seeking pleasant weather and outdoor activities.

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

The chart illustrates September temperature patterns in Yanai, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Yanai, September typically has an average temperature of 24°C (76°F), with highs reaching up to 31°C (88°F) and lows dropping to around 18°C (65°F).
JanFebMarAprMayJunJulAugSepOctNovDec454551576571798276685849
Data source: Temperature data for Yanai 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 Yanai

In Yanai in September, the precipitation amount is 215 mm (8.5 in) over the course of 13 days.

September Precipitation Trends in Yanai

The chart displays monthly precipitation patterns in Yanai, 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 Yanai, September typically receives around 215 mm (8.5 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec54791271461591893562212151744364
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Yanai

In Yanai in September humidity is 84%. With an average temperature of 24°C (76°F), this humidity feels like a warm, damp embrace that can make outdoor activities feel sticky and uncomfortable, requiring frequent breaks in the shade and plenty of hydration for travelers.

September Average Humidity in Yanai

This chart illustrates the average monthly humidity levels in Yanai, 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 Yanai is approximately 84%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec75%71%71%78%84%86%92%91%84%83%81%79%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Yanai

In Yanai 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 Yanai.

Maximum UV Index Levels in Yanai for September

The chart shows the monthly maximum UV Index (UVI) for Yanai 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 Yanai typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec458111111121210764
Data source: Yanai 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 Yanai Compares to Other Months

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

This table compares monthly weather conditions in Yanai, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather7°C (45°F)54 mm (2.1 inches)75%moderate
February Weather7°C (45°F)79 mm (3.1 inches)71%moderate
March Weather11°C (51°F)127 mm (5.0 inches)71%very high
April Weather14°C (58°F)146 mm (5.7 inches)78%extreme
May Weather18°C (65°F)159 mm (6.3 inches)84%extreme
June Weather22°C (72°F)189 mm (7.5 inches)86%extreme
July Weather26°C (79°F)355 mm (14.0 inches)92%extreme
August Weather28°C (82°F)221 mm (8.7 inches)91%extreme
September Weather24°C (76°F)215 mm (8.5 inches)84%very high
October Weather20°C (68°F)173 mm (6.8 inches)83%high
November Weather15°C (59°F)43 mm (1.7 inches)81%high
December Weather9°C (49°F)64 mm (2.5 inches)79%moderate

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