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September Weather in Hillsboro, United States

Last updated: June 24, 2025

In September, the average temperature in Hillsboro, United States is a pleasant 22°C (72°F). However, temperatures can fluctuate, with a minimum of 5°C (41°F) and a maximum reaching 35°C (95°F). Visitors should also prepare for some rain, as 80 mm (3.1 in) of precipitation is expected over 7 days. With an average humidity of 71%, the climate is comfortably warm and inviting.

September Temperature in Hillsboro

In September in Hillsboro, the average temperature is 22°C (72°F), with maximums reaching 35°C (95°F) and minimums dropping to as low as 5°C (41°F). This wide temperature range makes it essential for travelers to pack both light clothing for the warm days and warmer layers for the cooler 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 22°C (72°F), with highs reaching up to 35°C (95°F) and lows dropping to around 5°C (41°F).
JanFebMarAprMayJunJulAugSepOctNovDec333347556577807772574538
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 80 mm (3.1 in) during a span 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 80 mm (3.1 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec32338073175967913880972929
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 71%. With an average temperature of 22°C (72°F), this humidity feels like the air is thick and slightly stifling, making outdoor activities require frequent breaks to stay hydrated and cool.

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 71%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%78%70%73%82%82%81%78%71%71%81%84%
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 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3679101111109743
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 Weather0°C (33°F)32 mm (1.3 inches)76%moderate
February Weather1°C (34°F)33 mm (1.3 inches)77%high
March Weather8°C (47°F)80 mm (3.1 inches)70%high
April Weather13°C (55°F)73 mm (2.9 inches)73%very high
May Weather19°C (66°F)175 mm (6.9 inches)82%very high
June Weather25°C (78°F)95 mm (3.8 inches)82%extreme
July Weather27°C (80°F)79 mm (3.1 inches)81%extreme
August Weather25°C (77°F)138 mm (5.4 inches)78%very high
September Weather22°C (72°F)80 mm (3.1 inches)71%very high
October Weather14°C (57°F)97 mm (3.8 inches)71%high
November Weather7°C (45°F)29 mm (1.1 inches)81%moderate
December Weather3°C (38°F)29 mm (1.1 inches)84%moderate

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