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September Weather in Hillsborough, United States

Last updated: June 24, 2025

In September, the average temperature in Hillsborough, United States hovers around 21°C (70°F). You can expect a minimum of 5°C (42°F) and a maximum of 35°C (95°F). During this time, precipitation averages 92 mm (3.6 in) over approximately 9 days, contributing to a comfortable average humidity of 68%. Prepare accordingly for the diverse weather!

September Temperature in Hillsborough

In September in Hillsborough, the average temperature is 21°C (70°F), with maximums reaching 35°C (95°F) and minimums dropping as low as 5°C (42°F). This diverse range in temperatures makes it essential to pack for both warm days and cooler evenings during your travels.

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 21°C (70°F), with highs reaching up to 35°C (95°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec343742526272777569594538
Data source: Temperature data for Hillsborough 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 Hillsborough

In Hillsborough in September, the precipitation amount is 92 mm (3.6 in) during 9 days, indicating a relatively wet period for the region.

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 92 mm (3.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec671061071051281011341389212783104
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Hillsborough

In Hillsborough in September humidity is 68%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making the air feel slightly heavy and sticky, which can be quite exhausting for travelers.

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 68%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%81%78%70%69%62%65%68%74%82%80%
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 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 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 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356810101098642
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.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)67 mm (2.6 inches)84%moderate
February Weather3°C (37°F)106 mm (4.2 inches)82%moderate
March Weather6°C (42°F)107 mm (4.2 inches)81%high
April Weather11°C (53°F)105 mm (4.1 inches)78%very high
May Weather17°C (62°F)128 mm (5.0 inches)69%very high
June Weather22°C (72°F)101 mm (4.0 inches)69%very high
July Weather25°C (78°F)134 mm (5.3 inches)62%very high
August Weather24°C (75°F)138 mm (5.4 inches)65%very high
September Weather21°C (70°F)92 mm (3.6 inches)68%very high
October Weather15°C (60°F)127 mm (5.0 inches)74%high
November Weather7°C (45°F)83 mm (3.3 inches)82%moderate
December Weather3°C (38°F)104 mm (4.1 inches)80%low

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