September Weather in Watertown, United States

Last updated: June 24, 2025

In September, the average temperature in Watertown, United States hovers around 19°C (67°F). You can expect a minimum chill of 5°C (41°F) and heat peaks reaching up to 34°C (93°F). With an average precipitation of 105 mm (4.1 in) spread across 9 days, the air carries a humidity level of 68%. Prepare for a mix of weather as you enjoy this vibrant locale!

September Temperature in Watertown

In September in Watertown, the average temperature is 19°C (67°F), with maximums reaching 34°C (93°F) and minimums dropping as low as 5°C (41°F). This varied climate makes Watertown an ideal destination for travelers looking to experience both warm and cooler weather.

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

The chart illustrates September temperature patterns in Watertown, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Watertown, September typically has an average temperature of 19°C (67°F), with highs reaching up to 34°C (93°F) and lows dropping to around 5°C (41°F).

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

September Precipitation in Watertown

In Watertown in September, the total precipitation amount reaches 105 mm (4.1 in) over the course of 9 days.

September Precipitation Trends in Watertown

The chart displays monthly precipitation patterns in Watertown, 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 Watertown, September typically receives around 105 mm (4.1 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 Watertown

In Watertown in September, humidity is 68%. With an average temperature of 19°C (67°F), this humidity feels like a warm, enveloping blanket, making travel pleasant yet slightly muggy, which can be refreshing while exploring but may require occasional breaks to stay comfortable.

September Average Humidity in Watertown

This chart illustrates the average monthly humidity levels in Watertown, 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 Watertown is approximately 68%, 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 Watertown

In Watertown 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 Watertown.

Maximum UV Index Levels in Watertown for September

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

Data source: Watertown 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 Watertown Compares to Other Months

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

This table compares monthly weather conditions in Watertown, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	0°C (32°F)	69 mm (2.7 inches)	84%	moderate
February Weather	1°C (34°F)	93 mm (3.7 inches)	82%	moderate
March Weather	4°C (39°F)	91 mm (3.6 inches)	81%	high
April Weather	9°C (49°F)	130 mm (5.1 inches)	78%	very high
May Weather	15°C (60°F)	110 mm (4.3 inches)	69%	very high
June Weather	20°C (69°F)	99 mm (3.9 inches)	69%	very high
July Weather	24°C (75°F)	143 mm (5.6 inches)	62%	very high
August Weather	23°C (74°F)	94 mm (3.7 inches)	65%	very high
September Weather	19°C (67°F)	105 mm (4.1 inches)	68%	very high
October Weather	14°C (57°F)	138 mm (5.4 inches)	74%	high
November Weather	6°C (44°F)	93 mm (3.7 inches)	82%	moderate
December Weather	2°C (36°F)	124 mm (4.9 inches)	80%	low