September Weather in Hillsborough, United States

Last updated: June 24, 2025

In September, the average temperature in Hillsborough, United States hovers around 23°C (74°F). Expect a minimum of 9°C (48°F) and a maximum of 35°C (96°F), making it a month of delightful warmth. With an average precipitation of 128 mm (5.1 in) over 9 days, you'll want to be prepared for some rain. Additionally, the average humidity sits at a comfortable 79%, contributing to the area's lush ambiance.

September Temperature in Hillsborough

In September in Hillsborough, the average temperature is 23°C (74°F). Maximums can reach 35°C (96°F), while minimums can drop as low as 9°C (48°F). Overall, this month offers a warm climate, making it an ideal time for outdoor activities and exploration.

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

The chart illustrates September temperature patterns in Hillsborough, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Hillsborough, September typically has an average temperature of 23°C (74°F), with highs reaching up to 35°C (96°F) and lows dropping to around 9°C (48°F).

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

September Precipitation in Hillsborough

In Hillsborough in September, the precipitation amount is 128 mm (5.1 in) over the course of 9 days.

September Precipitation Trends in Hillsborough

The chart displays monthly precipitation patterns in Hillsborough, 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 Hillsborough, September typically receives around 128 mm (5.1 inches) of precipitation spread over approximately 9 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 Hillsborough

In Hillsborough in September, humidity is 79%. With an average temperature of 23°C (74°F), this humidity feels like a warm, enveloping blanket that can make outdoor activities a bit less comfortable, urging travelers to seek shade and hydration throughout the day.

September Average Humidity in Hillsborough

This chart illustrates the average monthly humidity levels in Hillsborough, 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 Hillsborough is approximately 79%, 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 Hillsborough

In Hillsborough 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 Hillsborough.

Maximum UV Index Levels in Hillsborough for September

The chart shows the monthly maximum UV Index (UVI) for Hillsborough 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 Hillsborough typically reaches 9, which falls under the very high exposure category.

Data source: Hillsborough 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 Hillsborough Compares to Other Months

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

This table compares monthly weather conditions in Hillsborough, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	6°C (43°F)	89 mm (3.5 inches)	85%	moderate
February Weather	9°C (48°F)	117 mm (4.6 inches)	82%	high
March Weather	11°C (53°F)	84 mm (3.3 inches)	81%	very high
April Weather	16°C (62°F)	116 mm (4.6 inches)	80%	very high
May Weather	21°C (70°F)	118 mm (4.6 inches)	81%	extreme
June Weather	24°C (76°F)	121 mm (4.8 inches)	81%	extreme
July Weather	27°C (80°F)	114 mm (4.5 inches)	81%	extreme
August Weather	26°C (78°F)	128 mm (5.1 inches)	80%	very high
September Weather	23°C (74°F)	128 mm (5.1 inches)	79%	very high
October Weather	18°C (65°F)	97 mm (3.8 inches)	80%	very high
November Weather	10°C (51°F)	81 mm (3.2 inches)	85%	moderate
December Weather	8°C (46°F)	107 mm (4.2 inches)	86%	moderate