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September Weather in Si'en, China

Last updated: August 22, 2025

In September, the average temperature in Si'en, China reaches a warm 27°C (80°F). Expect a minimum of 18°C (64°F) and a maximum of 36°C (97°F). Be prepared for some rain, as precipitation totals around 170 mm (6.7 in) spread over 19 days, with an average humidity of 66%. Enjoy the balmy weather, but don’t forget your umbrella!

September Temperature in Si'en

In September in Si'en, the average temperature is 27°C (80°F). Maximums can reach 36°C (97°F) and minimums can be as low as 18°C (64°F). It's an ideal time to visit for warm-weather activities while still enjoying cooler evenings.

September Weather in Si'en: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Si'en, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Si'en, September typically has an average temperature of 27°C (80°F), with highs reaching up to 36°C (97°F) and lows dropping to around 18°C (64°F).
JanFebMarAprMayJunJulAugSepOctNovDec525463697680828280706354
Data source: Temperature data for Si'en 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 Si'en

In Si'en in September, the precipitation amount is 170 mm (6.7 in) over the course of 19 days.

September Precipitation Trends in Si'en

The chart displays monthly precipitation patterns in Si'en, 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 Si'en, September typically receives around 170 mm (6.7 inches) of precipitation spread over approximately 19 days.
JanFebMarAprMayJunJulAugSepOctNovDec80941841912924292582611701319056
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Si'en

In Si'en in September, humidity is 66%. With an average temperature of 27°C (80°F), this humidity feels like a warm, sticky embrace, making travel a bit more challenging as you may find yourself perspiring more quickly while exploring, but it's also perfect for a refreshing dip in nearby waters.

September Average Humidity in Si'en

This chart illustrates the average monthly humidity levels in Si'en, 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 Si'en is approximately 66%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec59%67%70%67%84%87%89%86%66%66%69%68%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Si'en

In Si'en 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 Si'en.

Maximum UV Index Levels in Si'en for September

The chart shows the monthly maximum UV Index (UVI) for Si'en 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 Si'en typically reaches 11, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec79111113121313111086
Data source: Si'en 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 Si'en Compares to Other Months

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

This table compares monthly weather conditions in Si'en, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather11°C (52°F)80 mm (3.1 inches)59%high
February Weather12°C (55°F)94 mm (3.7 inches)67%very high
March Weather17°C (63°F)184 mm (7.2 inches)70%extreme
April Weather20°C (69°F)191 mm (7.5 inches)67%extreme
May Weather24°C (76°F)292 mm (11.5 inches)84%extreme
June Weather27°C (80°F)429 mm (16.9 inches)87%extreme
July Weather28°C (83°F)258 mm (10.1 inches)89%extreme
August Weather28°C (83°F)261 mm (10.3 inches)86%extreme
September Weather27°C (80°F)170 mm (6.7 inches)66%extreme
October Weather21°C (71°F)131 mm (5.1 inches)66%very high
November Weather17°C (63°F)89 mm (3.5 inches)69%very high
December Weather12°C (54°F)56 mm (2.2 inches)68%high

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