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September Weather in Plymouth, United States

Last updated: June 24, 2025

In Plymouth, United States, the average temperature in September hovers around 18°C (64°F). Expect a range where temperatures can dip to a chilly 3°C (38°F) and soar to a warm 32°C (89°F). This month also brings about 82 mm (3.2 in) of precipitation over approximately 10 days, resulting in a high average humidity of 79%.

September Temperature in Plymouth

In September in Plymouth, the average temperature is 18°C (64°F). Maximums can reach 32°C (89°F), and minimums can be as low as 3°C (38°F). This range makes it a great time for travelers to enjoy both warm days and cooler evenings.

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 18°C (64°F), with highs reaching up to 32°C (89°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec222234435667737064513729
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 total precipitation amount is 82 mm (3.2 in) observed over a span of 10 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 82 mm (3.2 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec48475710411610210889821074448
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 79%. With an average temperature of 18°C (64°F), this humidity feels like a warm, sticky embrace that can make outdoor activities more challenging but also creates a lush, vibrant atmosphere that's perfect for exploring local culture and scenery.

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 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%85%85%85%78%80%78%76%79%83%88%82%
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 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check 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 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec24589101097532
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-6°C (22°F)48 mm (1.9 inches)85%low
February Weather-5°C (23°F)47 mm (1.9 inches)85%moderate
March Weather1°C (34°F)57 mm (2.3 inches)85%moderate
April Weather6°C (43°F)104 mm (4.1 inches)85%very high
May Weather13°C (56°F)116 mm (4.6 inches)78%very high
June Weather19°C (67°F)102 mm (4.0 inches)80%very high
July Weather23°C (73°F)108 mm (4.3 inches)78%very high
August Weather21°C (71°F)89 mm (3.5 inches)76%very high
September Weather18°C (64°F)82 mm (3.2 inches)79%high
October Weather11°C (51°F)107 mm (4.2 inches)83%moderate
November Weather3°C (37°F)44 mm (1.7 inches)88%moderate
December Weather-1°C (30°F)48 mm (1.9 inches)81%low

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