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September Weather in Watertown, United States

Last updated: June 24, 2025

In Watertown, United States, the average temperature in September hovers around 17°C (62°F), with a minimum dipping to 1°C (35°F) and a maximum reaching up to 32°C (91°F). Expect about 84 mm (3.3 in) of precipitation spread over 9 days, contributing to an average humidity level of 82%. Embrace the variability of weather as you explore this captivating destination!

September Temperature in Watertown

In September in Watertown, the average temperature is 17°C (62°F). Maximum temperatures can reach 32°C (91°F), while the minimum can drop as low as 1°C (35°F). Be prepared for a wide range of temperatures, making it essential to pack both light clothing and warmer layers for your travels.

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 17°C (62°F), with highs reaching up to 32°C (91°F) and lows dropping to around 1°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec151430405670736962453223
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 84 mm (3.3 in) spread over 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 84 mm (3.3 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec2217486591848111384802533
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Watertown

In Watertown in September, humidity is 82%. With an average temperature of 17°C (62°F), this humidity feels like a thick blanket enveloping you, making every step feel heavier and the air thicker, which can be quite exhausting for 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 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%89%81%82%76%81%82%83%82%82%87%84%
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.
JanFebMarAprMayJunJulAugSepOctNovDec3567910998532
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 Weather-10°C (15°F)22 mm (0.9 inches)85%moderate
February Weather-10°C (14°F)17 mm (0.7 inches)89%moderate
March Weather-1°C (31°F)48 mm (1.9 inches)81%high
April Weather5°C (41°F)65 mm (2.6 inches)82%high
May Weather13°C (56°F)90 mm (3.6 inches)76%very high
June Weather21°C (70°F)84 mm (3.3 inches)81%very high
July Weather23°C (73°F)81 mm (3.2 inches)82%very high
August Weather21°C (70°F)113 mm (4.4 inches)83%very high
September Weather17°C (62°F)84 mm (3.3 inches)82%very high
October Weather7°C (46°F)80 mm (3.1 inches)82%moderate
November Weather0°C (33°F)25 mm (1.0 inches)87%moderate
December Weather-5°C (23°F)33 mm (1.3 inches)84%low

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