September Weather in Stonington, United States

Last updated: June 24, 2025

In Stonington, United States, the average temperature in September hovers around 20°C (68°F), providing a pleasant atmosphere for locals and visitors alike. Temperatures can dip to a cool 10°C (51°F) or rise to a comfortable 27°C (82°F). Be prepared for some rain, as 101 mm (4.0 in) of precipitation typically falls over 9 days, complemented by an average humidity level of 75%. Enjoy the vibrant climate!

September Temperature in Stonington

In September in Stonington, the average temperature is 20°C (68°F), with maximums reaching 27°C (82°F) and minimums dropping to as low as 10°C (51°F). This pleasant climate makes it an ideal time for travelers looking to explore and enjoy outdoor activities.

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

The chart illustrates September temperature patterns in Stonington, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Stonington, September typically has an average temperature of 20°C (68°F), with highs reaching up to 27°C (82°F) and lows dropping to around 10°C (51°F).

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

September Precipitation in Stonington

In Stonington in September, the total precipitation amount is 101 mm (4.0 in), occurring over a span of 9 days.

September Precipitation Trends in Stonington

The chart displays monthly precipitation patterns in Stonington, 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 Stonington, September typically receives around 101 mm (4.0 inches) of precipitation spread over approximately 9 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Stonington

In Stonington in September, humidity is 75%. With an average temperature of 20°C (68°F), this humidity feels like a warm, muggy embrace that can leave travelers feeling sticky and exhausted.

September Average Humidity in Stonington

This chart illustrates the average monthly humidity levels in Stonington, 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 Stonington is approximately 75%, 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 Stonington

In Stonington 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 Stonington.

Maximum UV Index Levels in Stonington for September

The chart shows the monthly maximum UV Index (UVI) for Stonington 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 Stonington typically reaches 8, which falls under the very high exposure category.

Data source: Stonington 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 Stonington Compares to Other Months

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

This table compares monthly weather conditions in Stonington, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	2°C (35°F)	83 mm (3.3 inches)	84%	moderate
February Weather	2°C (36°F)	109 mm (4.3 inches)	84%	moderate
March Weather	4°C (39°F)	108 mm (4.3 inches)	82%	high
April Weather	8°C (47°F)	136 mm (5.3 inches)	79%	very high
May Weather	13°C (55°F)	119 mm (4.7 inches)	75%	very high
June Weather	18°C (64°F)	84 mm (3.3 inches)	78%	very high
July Weather	22°C (72°F)	115 mm (4.5 inches)	76%	very high
August Weather	22°C (73°F)	101 mm (4.0 inches)	76%	very high
September Weather	20°C (68°F)	101 mm (4.0 inches)	75%	very high
October Weather	16°C (60°F)	157 mm (6.2 inches)	75%	high
November Weather	9°C (49°F)	113 mm (4.4 inches)	80%	moderate
December Weather	4°C (40°F)	141 mm (5.6 inches)	80%	low