September Weather in Plymouth, United States

Last updated: June 24, 2025

In September, the average temperature in Plymouth, United States is a pleasant 21°C (71°F), making it an ideal time to explore. However, be prepared for a temperature range that can dip to a minimum of 7°C (44°F) and peak at 39°C (103°F). Expect 10 mm (0.4 in) of precipitation spread over just 2 days, contributing to an average humidity of 44%.

September Temperature in Plymouth

In September in Plymouth, the average temperature is 21°C (71°F). Maximums can reach 39°C (103°F) and minimums can be as low as 7°C (44°F). Be sure to pack both light clothing for the heat and a warm layer for 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 21°C (71°F), with highs reaching up to 39°C (103°F) and lows dropping to around 7°C (44°F).

Data source: Temperature data for Plymouth generated using information from the Copernicus Climate Change Service.

September Precipitation in Plymouth

In Plymouth in September, the precipitation amount is 10 mm (0.4 in) over a period of 2 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 10 mm (0.4 inches) of precipitation spread over approximately 2 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Plymouth

In Plymouth in September humidity is 44%. With an average temperature of 21°C (71°F), this humidity feels like a comfortable and refreshing climate for traveling, allowing for enjoyable outdoor activities and leisurely explorations without feeling too sticky or oppressive.

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 44%, offering insight into how humid the weather typically is during this month.

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 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For 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 9, which falls under the very high exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	8°C (47°F)	191 mm (7.5 inches)	84%	moderate
February Weather	8°C (48°F)	190 mm (7.5 inches)	84%	moderate
March Weather	10°C (50°F)	210 mm (8.3 inches)	83%	very high
April Weather	13°C (57°F)	96 mm (3.8 inches)	81%	very high
May Weather	17°C (62°F)	57 mm (2.2 inches)	74%	very high
June Weather	22°C (72°F)	6 mm (0.2 inches)	64%	extreme
July Weather	25°C (77°F)	0 mm (0.0 inches)	44%	extreme
August Weather	24°C (76°F)	0 mm (0.0 inches)	36%	very high
September Weather	21°C (71°F)	10 mm (0.4 inches)	44%	very high
October Weather	16°C (61°F)	49 mm (1.9 inches)	65%	high
November Weather	11°C (52°F)	103 mm (4.1 inches)	84%	moderate
December Weather	8°C (46°F)	156 mm (6.1 inches)	83%	moderate