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September Weather in Plymouth, United States

Last updated: June 24, 2025

In September, the average temperature in Plymouth, United States hovers around 20°C (68°F). You'll experience a comfortable range, with minimums dipping to 5°C (41°F) and maximums soaring up to 33°C (92°F). Expect 77 mm (3.0 in) of precipitation over about 9 days, contributing to a moderately high humidity level of 78%.

September Temperature in Plymouth

In September in Plymouth, the average temperature is 20°C (68°F), with maximums reaching 33°C (92°F) and minimums dropping as low as 5°C (41°F). This climate makes Plymouth an ideal destination for travelers seeking a pleasant mix of warm days and cool nights.

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

The chart illustrates September temperature patterns in Plymouth, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Plymouth, September typically has an average temperature of 20°C (68°F), with highs reaching up to 33°C (92°F) and lows dropping to around 5°C (41°F).
JanFebMarAprMayJunJulAugSepOctNovDec293240506270747267574134
Data source: Temperature data for Plymouth 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 Plymouth

In Plymouth in September, the precipitation amount is 77 mm (3.0 in) over the course of 9 days.

September Precipitation Trends in Plymouth

The chart displays monthly precipitation patterns in Plymouth, 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 Plymouth, September typically receives around 77 mm (3.0 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec7793961171271331268377959081
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Plymouth

In Plymouth in September humidity is 78%. With an average temperature of 20°C (68°F), this humidity feels like a warm, enveloping blanket that makes exploring the sights a bit sticky, so travelers should stay hydrated and take frequent breaks in the shade.

September Average Humidity in Plymouth

This chart illustrates the average monthly humidity levels in Plymouth, 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 Plymouth is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%87%88%81%82%81%78%78%82%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Plymouth

In Plymouth 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 Plymouth.

Maximum UV Index Levels in Plymouth for September

The chart shows the monthly maximum UV Index (UVI) for Plymouth 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 Plymouth typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Plymouth 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 Plymouth Compares to Other Months

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

This table compares monthly weather conditions in Plymouth, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)77 mm (3.0 inches)88%moderate
February Weather0°C (32°F)93 mm (3.7 inches)87%moderate
March Weather4°C (40°F)96 mm (3.8 inches)87%high
April Weather10°C (50°F)117 mm (4.6 inches)87%very high
May Weather17°C (62°F)127 mm (5.0 inches)81%very high
June Weather21°C (71°F)133 mm (5.2 inches)82%very high
July Weather24°C (75°F)126 mm (5.0 inches)81%very high
August Weather22°C (72°F)83 mm (3.3 inches)78%very high
September Weather20°C (68°F)77 mm (3.0 inches)78%very high
October Weather14°C (57°F)95 mm (3.7 inches)82%high
November Weather5°C (41°F)90 mm (3.6 inches)89%moderate
December Weather1°C (35°F)81 mm (3.2 inches)86%low

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