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September Weather in Watertown, United States

Last updated: June 24, 2025

In September, the average temperature in Watertown, United States hovers around 23°C (74°F). However, be prepared for a range of temperatures, with minimums dipping to 7°C (45°F) and maximums soaring up to 36°C (97°F). During this period, expect about 130 mm (5.1 in) of precipitation spread across 10 days, contributing to an average humidity of 64%. Plan accordingly to enjoy your stay!

September Temperature in Watertown

In September in Watertown, the average temperature is 23°C (74°F). Maximum temperatures can reach 36°C (97°F), while minimums can drop as low as 7°C (45°F). This range makes it essential for travelers to pack both light clothing for the warm days and warmer layers for the cooler evenings.

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 23°C (74°F), with highs reaching up to 36°C (97°F) and lows dropping to around 7°C (45°F).
JanFebMarAprMayJunJulAugSepOctNovDec414653597076807874634946
Data source: Temperature data for Watertown 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 Watertown

In Watertown in September, the precipitation amount is 130 mm (5.1 in) over a period of 10 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 130 mm (5.1 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec10919017615112314913112413014081152
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Watertown

In Watertown in September, humidity is 64%. With an average temperature of 23°C (74°F), this humidity feels like a warm blanket wrapping around you, making outdoor exploration enjoyable yet slightly sticky, so it's best to stay hydrated and take breaks in the shade while traveling.

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 64%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%87%85%82%83%82%78%67%64%75%87%89%
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 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 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36710101111109753
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.
 TemperaturePrecipitationHumidityUV
January Weather5°C (41°F)109 mm (4.3 inches)87%moderate
February Weather8°C (46°F)190 mm (7.5 inches)87%high
March Weather12°C (53°F)176 mm (6.9 inches)85%high
April Weather15°C (60°F)151 mm (5.9 inches)82%very high
May Weather21°C (70°F)123 mm (4.8 inches)83%very high
June Weather25°C (76°F)149 mm (5.9 inches)82%extreme
July Weather26°C (80°F)131 mm (5.1 inches)78%extreme
August Weather25°C (78°F)124 mm (4.9 inches)67%very high
September Weather23°C (74°F)130 mm (5.1 inches)64%very high
October Weather17°C (64°F)140 mm (5.5 inches)74%high
November Weather9°C (49°F)81 mm (3.2 inches)87%moderate
December Weather8°C (46°F)151 mm (6.0 inches)88%moderate

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