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September Weather in Hopkinton, United States

Last updated: June 24, 2025

In Hopkinton, United States, the average temperature in September hovers around 19°C (66°F), with a nighttime minimum of 2°C (35°F) and daytime highs reaching up to 33°C (91°F). Expect about 124 mm (4.9 in) of precipitation over 9 days, accompanied by an average humidity level of 74%, creating a diverse and vibrant climate for the month.

September Temperature in Hopkinton

In September in Hopkinton, the average temperature is 19°C (66°F), with maximums reaching 33°C (91°F) and minimums dropping as low as 2°C (35°F). This wide range in temperature makes it essential for travelers to pack both light clothing for the warm days and warmer layers for the cooler nights.

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

The chart illustrates September temperature patterns in Hopkinton, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Hopkinton, September typically has an average temperature of 19°C (66°F), with highs reaching up to 33°C (91°F) and lows dropping to around 2°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec212237476172757166523730
Data source: Temperature data for Hopkinton 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 Hopkinton

In Hopkinton in September, the precipitation amount is 124 mm (4.9 in) over the course of 9 days.

September Precipitation Trends in Hopkinton

The chart displays monthly precipitation patterns in Hopkinton, 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 Hopkinton, September typically receives around 124 mm (4.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec4859678015812287841241324843
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Hopkinton

In Hopkinton in September humidity is 74%. With an average temperature of 19°C (66°F), this humidity feels like a warm, enveloping blanket, making it ideal for leisurely outdoor exploration but potentially heavy for those not accustomed to tropical conditions.

September Average Humidity in Hopkinton

This chart illustrates the average monthly humidity levels in Hopkinton, 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 Hopkinton is approximately 74%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%85%84%83%75%79%75%69%74%79%88%82%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Hopkinton

In Hopkinton 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 Hopkinton.

Maximum UV Index Levels in Hopkinton for September

The chart shows the monthly maximum UV Index (UVI) for Hopkinton 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 Hopkinton typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34589111098533
Data source: Hopkinton 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 Hopkinton Compares to Other Months

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

This table compares monthly weather conditions in Hopkinton, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-6°C (21°F)48 mm (1.9 inches)84%moderate
February Weather-5°C (22°F)59 mm (2.3 inches)85%moderate
March Weather3°C (37°F)67 mm (2.6 inches)84%moderate
April Weather8°C (47°F)80 mm (3.1 inches)83%very high
May Weather16°C (61°F)158 mm (6.2 inches)75%very high
June Weather22°C (72°F)122 mm (4.8 inches)79%extreme
July Weather24°C (75°F)87 mm (3.4 inches)75%very high
August Weather22°C (72°F)84 mm (3.3 inches)69%very high
September Weather19°C (66°F)124 mm (4.9 inches)74%very high
October Weather11°C (52°F)131 mm (5.2 inches)79%moderate
November Weather3°C (37°F)48 mm (1.9 inches)88%moderate
December Weather-1°C (30°F)43 mm (1.7 inches)82%moderate

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