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September Weather in Waterville, United States

Last updated: June 24, 2025

In Waterville, United States, the average temperature in September is a pleasant 22°C (72°F). However, temperatures can fluctuate, with a minimum of 5°C (42°F) and a maximum soaring to 37°C (100°F). Expect about 63 mm (2.5 in) of precipitation over approximately 7 days, contributing to an average humidity of 71%. This month offers a diverse climate experience, making it an intriguing time to visit!

September Temperature in Waterville

In September, in Waterville, the average temperature is 22°C (72°F). Maximum can reach 37°C (100°F), and minimum can be as low as 5°C (42°F). This range makes it an ideal destination for travelers looking to enjoy both warm and mild weather.

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 22°C (72°F), with highs reaching up to 37°C (100°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec303045536577807672554335
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 63 mm (2.5 in) over a span of 7 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 63 mm (2.5 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec282887692011029198631233326
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 71%. With an average temperature of 22°C (72°F), this humidity feels like the air is thick and slightly stifling, making outdoor activities require frequent breaks to stay hydrated and cool.

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 71%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%78%70%73%82%82%81%78%71%71%81%84%
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 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 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109643
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-1°C (30°F)28 mm (1.1 inches)76%moderate
February Weather-1°C (30°F)28 mm (1.1 inches)77%moderate
March Weather7°C (45°F)87 mm (3.4 inches)70%high
April Weather12°C (53°F)69 mm (2.7 inches)73%very high
May Weather18°C (65°F)201 mm (7.9 inches)82%very high
June Weather25°C (78°F)102 mm (4.0 inches)82%extreme
July Weather27°C (81°F)91 mm (3.6 inches)81%extreme
August Weather25°C (77°F)98 mm (3.9 inches)78%very high
September Weather22°C (72°F)63 mm (2.5 inches)71%very high
October Weather13°C (55°F)123 mm (4.9 inches)71%high
November Weather6°C (43°F)33 mm (1.3 inches)81%moderate
December Weather2°C (36°F)26 mm (1.0 inches)84%moderate

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