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September Weather in Dorchester, United States

Last updated: June 24, 2025

In September, the average temperature in Dorchester, United States is a pleasant 21°C (70°F). However, temperatures can vary significantly, dipping to a minimum of 5°C (42°F) and soaring up to a sweltering 37°C (98°F). Expect about 81 mm (3.2 in) of precipitation spread over 8 days, and don't forget the average humidity level, which sits at a comfortable 75%.

September Temperature in Dorchester

In September in Dorchester, the average temperature is 21°C (70°F). Maximum temperatures can reach 37°C (98°F), while minimums can dip as low as 5°C (42°F). Travelers should be prepared for a wide range of temperatures, so it's advisable to pack both lightweight clothing and warmer layers for the cooler evenings.

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

The chart illustrates September temperature patterns in Dorchester, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Dorchester, September typically has an average temperature of 21°C (70°F), with highs reaching up to 37°C (98°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec272742516377797570534133
Data source: Temperature data for Dorchester 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 Dorchester

In Dorchester in September, the precipitation amount is 81 mm (3.2 in) over the course of 8 days.

September Precipitation Trends in Dorchester

The chart displays monthly precipitation patterns in Dorchester, 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 Dorchester, September typically receives around 81 mm (3.2 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec32269547145976582811102740
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Dorchester

In Dorchester in September, humidity is 75%. With an average temperature of 21°C (70°F), this humidity feels like a warm, enveloping blanket that makes exploring the area feel slightly sticky, requiring travelers to stay hydrated and take occasional breaks in the shade to fully enjoy their adventures.

September Average Humidity in Dorchester

This chart illustrates the average monthly humidity levels in Dorchester, 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 Dorchester is approximately 75%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%80%73%75%78%82%83%81%75%75%82%83%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Dorchester

In Dorchester 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 Dorchester.

Maximum UV Index Levels in Dorchester for September

The chart shows the monthly maximum UV Index (UVI) for Dorchester 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 Dorchester typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098643
Data source: Dorchester 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 Dorchester Compares to Other Months

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

This table compares monthly weather conditions in Dorchester, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (27°F)32 mm (1.3 inches)76%moderate
February Weather-3°C (27°F)26 mm (1.0 inches)80%moderate
March Weather6°C (42°F)95 mm (3.7 inches)73%high
April Weather11°C (51°F)47 mm (1.8 inches)74%very high
May Weather17°C (63°F)145 mm (5.7 inches)78%very high
June Weather25°C (77°F)97 mm (3.8 inches)82%extreme
July Weather26°C (79°F)64 mm (2.5 inches)83%very high
August Weather24°C (76°F)82 mm (3.2 inches)80%very high
September Weather21°C (70°F)81 mm (3.2 inches)75%very high
October Weather12°C (53°F)110 mm (4.3 inches)75%high
November Weather5°C (41°F)27 mm (1.1 inches)82%moderate
December Weather0°C (33°F)40 mm (1.6 inches)83%moderate

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