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September Weather in Marietta-Alderwood, United States

Last updated: June 24, 2025

In Marietta-Alderwood, United States, the average temperature in September hovers around 15°C (60°F), with a minimum of 7°C (46°F) and a comfortable maximum of 27°C (81°F). Expect about 125 mm (4.9 in) of precipitation spread over 11 days, contributing to an average humidity of 76%. Perfect for embracing the seasonal vibe!

September Temperature in Marietta-Alderwood

In September in Marietta-Alderwood, the average temperature is 15°C (60°F). Maximums can reach 27°C (81°F), while minimums can drop as low as 7°C (46°F). This makes Marietta-Alderwood a comfortable destination for travelers looking to enjoy mild weather and a pleasant outdoor experience.

September Weather in Marietta-Alderwood: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Marietta-Alderwood, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Marietta-Alderwood, September typically has an average temperature of 15°C (60°F), with highs reaching up to 27°C (81°F) and lows dropping to around 7°C (46°F).
JanFebMarAprMayJunJulAugSepOctNovDec413943485358636460514641
Data source: Temperature data for Marietta-Alderwood 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 Marietta-Alderwood

In Marietta-Alderwood in September, the precipitation amount is 125 mm (4.9 in) over the course of 11 days.

September Precipitation Trends in Marietta-Alderwood

The chart displays monthly precipitation patterns in Marietta-Alderwood, 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 Marietta-Alderwood, September typically receives around 125 mm (4.9 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec19918515612776582720125186261227
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Marietta-Alderwood

In Marietta-Alderwood in September humidity is 76%. With an average temperature of 15°C (60°F), this humidity feels like a warm, damp blanket wrapping around you, making outdoor activities a bit more challenging and urging you to stay hydrated while exploring the area.

September Average Humidity in Marietta-Alderwood

This chart illustrates the average monthly humidity levels in Marietta-Alderwood, 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 Marietta-Alderwood is approximately 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%85%86%86%81%83%84%77%76%88%87%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Marietta-Alderwood

In Marietta-Alderwood in September, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in Marietta-Alderwood, you can refer to this Hourly UV Index in Marietta-Alderwood.

Maximum UV Index Levels in Marietta-Alderwood for September

The chart shows the monthly maximum UV Index (UVI) for Marietta-Alderwood 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 Marietta-Alderwood typically reaches 6, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec235689986421
Data source: Marietta-Alderwood 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 Marietta-Alderwood Compares to Other Months

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

This table compares monthly weather conditions in Marietta-Alderwood, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (41°F)199 mm (7.8 inches)86%low
February Weather4°C (39°F)185 mm (7.3 inches)85%moderate
March Weather6°C (44°F)156 mm (6.2 inches)86%moderate
April Weather9°C (48°F)127 mm (5.0 inches)86%high
May Weather12°C (53°F)76 mm (3.0 inches)81%very high
June Weather15°C (59°F)58 mm (2.3 inches)83%very high
July Weather17°C (63°F)27 mm (1.1 inches)84%very high
August Weather18°C (64°F)19 mm (0.8 inches)77%very high
September Weather15°C (60°F)125 mm (4.9 inches)76%high
October Weather11°C (51°F)186 mm (7.3 inches)88%moderate
November Weather8°C (46°F)261 mm (10.3 inches)87%low
December Weather5°C (41°F)227 mm (8.9 inches)87%low

Compare Marietta-Alderwood's Climate with Cities Worldwide