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September Weather in Hillsboro, United States

Last updated: June 24, 2025

In Hillsboro, United States, the average temperature in September is a pleasant 21°C (70°F). Visitors can expect a range from a chilly 6°C (43°F) to a warm 34°C (93°F). The month sees an average precipitation of 66 mm (2.6 in) spread over 7 days, paired with a comfortable average humidity of 69%. Whether you're soaking up the sun or enjoying the cooler breezes, Hillsboro offers a delightful climate perfect for exploration!

September Temperature in Hillsboro

In September in Hillsboro, the average temperature is 21°C (70°F), with maximums reaching 34°C (93°F) and minimums dropping as low as 6°C (43°F). This makes it a great time to explore the area, as you can enjoy warm days and cool evenings.

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

The chart illustrates September temperature patterns in Hillsboro, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Hillsboro, September typically has an average temperature of 21°C (70°F), with highs reaching up to 34°C (93°F) and lows dropping to around 6°C (43°F).
JanFebMarAprMayJunJulAugSepOctNovDec293243526474777470584136
Data source: Temperature data for Hillsboro 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 Hillsboro

In Hillsboro in September, the precipitation amount is 66 mm (2.6 in) over a period of 7 days.

September Precipitation Trends in Hillsboro

The chart displays monthly precipitation patterns in Hillsboro, 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 Hillsboro, September typically receives around 66 mm (2.6 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec8081114104149103101108661198167
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Hillsboro

In Hillsboro in September humidity is 69%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making outdoor activities enjoyable but requiring occasional breaks for hydration and shade during your travels.

September Average Humidity in Hillsboro

This chart illustrates the average monthly humidity levels in Hillsboro, 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 Hillsboro is approximately 69%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%86%84%79%82%79%70%69%76%88%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Hillsboro

In Hillsboro 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 Hillsboro.

Maximum UV Index Levels in Hillsboro for September

The chart shows the monthly maximum UV Index (UVI) for Hillsboro 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 Hillsboro typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098643
Data source: Hillsboro 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 Hillsboro Compares to Other Months

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

This table compares monthly weather conditions in Hillsboro, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (30°F)80 mm (3.2 inches)87%moderate
February Weather0°C (33°F)81 mm (3.2 inches)85%moderate
March Weather6°C (43°F)114 mm (4.5 inches)86%high
April Weather11°C (52°F)104 mm (4.1 inches)84%very high
May Weather18°C (65°F)149 mm (5.8 inches)79%very high
June Weather23°C (75°F)103 mm (4.1 inches)82%extreme
July Weather25°C (77°F)101 mm (4.0 inches)79%very high
August Weather24°C (75°F)108 mm (4.2 inches)70%very high
September Weather21°C (70°F)66 mm (2.6 inches)69%very high
October Weather14°C (58°F)119 mm (4.7 inches)76%high
November Weather5°C (42°F)81 mm (3.2 inches)88%moderate
December Weather2°C (36°F)67 mm (2.7 inches)87%moderate

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