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September Weather in Sai, Japan

Last updated: August 23, 2025

In September, the average temperature in Sai, Japan hovers around 21°C (69°F). Expect lows of 15°C (59°F) and highs reaching 27°C (81°F). Be prepared for some rain, as 132 mm (5.2 in) of precipitation can fall across 12 days, contributing to an average humidity of 89%.

September Temperature in Sai

In September in Sai, the average temperature is 21°C (69°F). Maximum temperatures can reach 27°C (81°F), while the minimum can drop as low as 15°C (59°F). This pleasant weather makes it an ideal time for exploring outdoor activities and enjoying the local scenery.

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

The chart illustrates September temperature patterns in Sai, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sai, September typically has an average temperature of 21°C (69°F), with highs reaching up to 27°C (81°F) and lows dropping to around 15°C (59°F).
JanFebMarAprMayJunJulAugSepOctNovDec343340465259677269614938
Data source: Temperature data for Sai 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 Sai

In Sai in September, the precipitation amount is 132 mm (5.2 in) over the course of 12 days.

September Precipitation Trends in Sai

The chart displays monthly precipitation patterns in Sai, 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 Sai, September typically receives around 132 mm (5.2 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec1121179398104112110188132156131168
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Sai

In Sai in September, humidity is 89%. With an average temperature of 21°C (69°F), this humidity feels like a warm blanket enveloping you, making travel a bit sticky and requiring frequent breaks to cool off and stay hydrated.

September Average Humidity in Sai

This chart illustrates the average monthly humidity levels in Sai, 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 Sai is approximately 89%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec79%78%77%78%86%91%95%97%89%82%78%77%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Sai

In Sai in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Sai.

Maximum UV Index Levels in Sai for September

The chart shows the monthly maximum UV Index (UVI) for Sai 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 Sai typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec235891010118632
Data source: Sai 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 Sai Compares to Other Months

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

This table compares monthly weather conditions in Sai, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)112 mm (4.4 inches)79%low
February Weather1°C (34°F)117 mm (4.6 inches)78%moderate
March Weather4°C (40°F)93 mm (3.7 inches)77%moderate
April Weather8°C (46°F)98 mm (3.9 inches)78%very high
May Weather11°C (53°F)103 mm (4.1 inches)86%very high
June Weather15°C (59°F)112 mm (4.4 inches)91%very high
July Weather19°C (67°F)110 mm (4.3 inches)95%very high
August Weather22°C (72°F)187 mm (7.4 inches)97%extreme
September Weather21°C (69°F)132 mm (5.2 inches)89%very high
October Weather16°C (61°F)156 mm (6.1 inches)81%high
November Weather9°C (49°F)131 mm (5.1 inches)78%moderate
December Weather3°C (38°F)167 mm (6.6 inches)77%low

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