nomadseason

September Weather in Lewiston, United States

Last updated: June 24, 2025

In September, the average temperature in Lewiston, United States hovers around 19°C (66°F), offering a pleasant climate. Expect temperatures to range from a minimum of 9°C (48°F) to a maximum of 29°C (85°F). During this time, precipitation averages 73 mm (2.9 in) over 9 days, with humidity reaching around 76%. Embrace the mild conditions as you explore this charming locale!

September Temperature in Lewiston

In September in Lewiston, the average temperature is 19°C (66°F). Maximum can reach 29°C (85°F) and minimum can be as low as 9°C (48°F). This makes it an ideal time for traveling, offering pleasant weather for outdoor activities and sightseeing.

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

The chart illustrates September temperature patterns in Lewiston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Lewiston, September typically has an average temperature of 19°C (66°F), with highs reaching up to 29°C (85°F) and lows dropping to around 9°C (48°F).
JanFebMarAprMayJunJulAugSepOctNovDec293035435264737266564235
Data source: Temperature data for Lewiston generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Lewiston

In Lewiston in September, the precipitation amount is 73 mm (2.9 in), occurring over the course of 9 days.

September Precipitation Trends in Lewiston

The chart displays monthly precipitation patterns in Lewiston, 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 Lewiston, September typically receives around 73 mm (2.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec788772118998111585731288990
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Lewiston

In Lewiston in September, humidity is 76%. With an average temperature of 19°C (66°F), this humidity feels like a warm, thick blanket wrapping around you, making travel mildly uncomfortable and encouraging frequent breaks in shaded or air-conditioned areas.

September Average Humidity in Lewiston

This chart illustrates the average monthly humidity levels in Lewiston, 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 Lewiston is approximately 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%91%88%88%82%80%77%72%76%83%88%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Lewiston

In Lewiston in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Lewiston.

Maximum UV Index Levels in Lewiston for September

The chart shows the monthly maximum UV Index (UVI) for Lewiston 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 Lewiston typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2458910997532
Data source: Lewiston 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 Lewiston Compares to Other Months

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

This table compares monthly weather conditions in Lewiston, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)78 mm (3.1 inches)91%low
February Weather-1°C (30°F)87 mm (3.4 inches)91%moderate
March Weather2°C (35°F)71 mm (2.8 inches)88%moderate
April Weather6°C (43°F)118 mm (4.6 inches)88%very high
May Weather11°C (53°F)99 mm (3.9 inches)82%very high
June Weather18°C (64°F)81 mm (3.2 inches)79%very high
July Weather23°C (73°F)115 mm (4.5 inches)77%very high
August Weather22°C (73°F)85 mm (3.3 inches)72%very high
September Weather19°C (66°F)73 mm (2.9 inches)76%high
October Weather13°C (56°F)128 mm (5.0 inches)83%moderate
November Weather6°C (42°F)89 mm (3.5 inches)88%moderate
December Weather1°C (35°F)90 mm (3.5 inches)87%low

Compare Lewiston's Climate with Cities Worldwide