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September Weather in Waterville, United States

Last updated: June 24, 2025

In Waterville, United States, the average temperature in September hovers around 20°C (68°F), with lows dipping to 5°C (40°F) and highs peaking at 34°C (93°F). Expect a total precipitation of 59 mm (2.3 in) spread over 9 days, contributing to the area's notably high average humidity of 78%.

September Temperature in Waterville

In September in Waterville, the average temperature is 20°C (68°F), with maximums reaching up to 34°C (93°F) and minimums dropping as low as 5°C (40°F). It's a great time to visit for those who enjoy mild weather with the option of some warm days.

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

The chart illustrates September temperature patterns in Waterville, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Waterville, September typically has an average temperature of 20°C (68°F), with highs reaching up to 34°C (93°F) and lows dropping to around 5°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec283039496272767368564134
Data source: Temperature data for Waterville 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 Waterville

In Waterville in September, the precipitation amount is 59 mm (2.3 in) over the course of 9 days.

September Precipitation Trends in Waterville

The chart displays monthly precipitation patterns in Waterville, 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 Waterville, September typically receives around 59 mm (2.3 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec697284931451061128859928356
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Waterville

In Waterville in September humidity is 78%. With an average temperature of 20°C (68°F), this humidity feels like a warm, enveloping blanket that makes exploring the sights a bit sticky, so travelers should stay hydrated and take frequent breaks in the shade.

September Average Humidity in Waterville

This chart illustrates the average monthly humidity levels in Waterville, 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 Waterville is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%87%88%81%82%81%78%78%82%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Waterville

In Waterville 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 Waterville.

Maximum UV Index Levels in Waterville for September

The chart shows the monthly maximum UV Index (UVI) for Waterville 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 Waterville typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Waterville 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 Waterville Compares to Other Months

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

This table compares monthly weather conditions in Waterville, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)69 mm (2.7 inches)88%moderate
February Weather-1°C (30°F)72 mm (2.8 inches)87%moderate
March Weather4°C (40°F)84 mm (3.3 inches)87%high
April Weather10°C (49°F)93 mm (3.7 inches)87%very high
May Weather16°C (62°F)145 mm (5.7 inches)81%very high
June Weather22°C (72°F)106 mm (4.2 inches)82%very high
July Weather24°C (76°F)112 mm (4.4 inches)81%very high
August Weather23°C (74°F)88 mm (3.5 inches)78%very high
September Weather20°C (68°F)59 mm (2.3 inches)78%very high
October Weather14°C (57°F)92 mm (3.6 inches)82%high
November Weather5°C (41°F)83 mm (3.3 inches)89%moderate
December Weather1°C (35°F)56 mm (2.2 inches)86%low

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