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September Weather in Sunnyside, United States

Last updated: June 24, 2025

In September, the average temperature in Sunnyside, United States stands at a pleasant 20°C (68°F). However, be prepared for a possible minimum of 4°C (40°F) and a sweltering maximum of 40°C (104°F). During this month, expect 9 mm (0.4 in) of precipitation spread over 3 days, alongside an average humidity of 62%. Stay comfortable and enjoy your time!

September Temperature in Sunnyside

In September in Sunnyside, the average temperature is 20°C (68°F). The maximum can reach 40°C (104°F), while the minimum can drop as low as 4°C (40°F). Be prepared for a wide range of temperatures when traveling during this month.

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

The chart illustrates September temperature patterns in Sunnyside, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sunnyside, September typically has an average temperature of 20°C (68°F), with highs reaching up to 40°C (104°F) and lows dropping to around 4°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec343645546573807968534235
Data source: Temperature data for Sunnyside 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 Sunnyside

In Sunnyside in September, the precipitation amount is 9 mm (0.4 in) over a span of 3 days.

September Precipitation Trends in Sunnyside

The chart displays monthly precipitation patterns in Sunnyside, 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 Sunnyside, September typically receives around 9 mm (0.4 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec43432524167159263135
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Sunnyside

In Sunnyside in September, humidity is 62%. With an average temperature of 20°C (68°F), this humidity feels like a warm, balmy embrace that can make outdoor activities enjoyable in the early morning and late afternoon, but can become quite stifling during the midday heat, making it advisable to stay hydrated and take breaks in shaded areas while traveling.

September Average Humidity in Sunnyside

This chart illustrates the average monthly humidity levels in Sunnyside, 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 Sunnyside is approximately 62%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%87%84%81%82%79%63%62%83%89%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Sunnyside

In Sunnyside in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Sunnyside.

Maximum UV Index Levels in Sunnyside for September

The chart shows the monthly maximum UV Index (UVI) for Sunnyside 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 Sunnyside typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec23569101097532
Data source: Sunnyside 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 Sunnyside Compares to Other Months

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

This table compares monthly weather conditions in Sunnyside, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)43 mm (1.7 inches)86%low
February Weather2°C (36°F)43 mm (1.7 inches)86%moderate
March Weather7°C (45°F)25 mm (1.0 inches)87%moderate
April Weather12°C (54°F)24 mm (1.0 inches)84%high
May Weather18°C (65°F)16 mm (0.6 inches)81%very high
June Weather23°C (73°F)7 mm (0.3 inches)82%very high
July Weather27°C (80°F)1 mm (0.0 inches)79%very high
August Weather26°C (79°F)5 mm (0.2 inches)63%very high
September Weather20°C (68°F)9 mm (0.4 inches)62%high
October Weather12°C (53°F)26 mm (1.0 inches)83%moderate
November Weather5°C (42°F)31 mm (1.2 inches)89%moderate
December Weather1°C (35°F)35 mm (1.4 inches)88%low

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