September Weather in Hillsboro, United States

Last updated: June 24, 2025

In September, the average temperature in Hillsboro, United States is a pleasant 25°C (78°F), with daily highs reaching up to 38°C (100°F) and lows dipping to 10°C (51°F). Expect around 100 mm (3.9 in) of precipitation over 8 days, contributing to an average humidity level of 74%. Enjoy this vibrant climate!

September Temperature in Hillsboro

In September in Hillsboro, the average temperature is 25°C (78°F). The maximum can reach 38°C (100°F), and the minimum can be as low as 10°C (51°F). It's a great time to explore outdoor activities while enjoying the warm weather, but be prepared for both the heat and 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 25°C (78°F), with highs reaching up to 38°C (100°F) and lows dropping to around 10°C (51°F).

Data source: Temperature data for Hillsboro generated using information from the Copernicus Climate Change Service.

September Precipitation in Hillsboro

In Hillsboro in September, the precipitation amount is 100 mm (3.9 in) spread over the course of 8 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 100 mm (3.9 inches) of precipitation spread over approximately 8 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Hillsboro

In Hillsboro in September humidity is 74%. With an average temperature of 25°C (78°F), this humidity feels like you're enveloped in a warm, thick blanket, making outdoor activities feel more strenuous and necessitating frequent breaks and hydration for comfortable travel.

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 74%, offering insight into how humid the weather typically is during this month.

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 reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more 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 10, which falls under the very high exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (48°F)	109 mm (4.3 inches)	85%	moderate
February Weather	12°C (53°F)	159 mm (6.3 inches)	84%	high
March Weather	16°C (60°F)	126 mm (5.0 inches)	82%	very high
April Weather	18°C (64°F)	163 mm (6.4 inches)	82%	extreme
May Weather	23°C (74°F)	132 mm (5.2 inches)	82%	extreme
June Weather	26°C (79°F)	155 mm (6.1 inches)	79%	extreme
July Weather	27°C (81°F)	109 mm (4.3 inches)	82%	extreme
August Weather	27°C (81°F)	138 mm (5.4 inches)	77%	extreme
September Weather	25°C (78°F)	100 mm (3.9 inches)	74%	very high
October Weather	20°C (69°F)	96 mm (3.8 inches)	73%	very high
November Weather	13°C (55°F)	70 mm (2.8 inches)	85%	high
December Weather	11°C (52°F)	121 mm (4.8 inches)	88%	moderate