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September Weather in Lowell, United States

Last updated: June 24, 2025

In September, the average temperature in Lowell, United States hovers around 18°C (65°F), with extremes ranging from a chilly 0°C (33°F) to a sizzling 35°C (96°F). Expect some rain, as 113 mm (4.5 in) of precipitation typically falls over 10 days. Coupled with an average humidity of 79%, the weather can feel quite tropical.

September Temperature in Lowell

In September in Lowell, the average temperature is 18°C (65°F), with maximums reaching 35°C (96°F) and minimums dropping as low as 0°C (33°F). Be prepared for a variety of weather conditions during your travels, ranging from warm days to cooler nights.

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

The chart illustrates September temperature patterns in Lowell, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Lowell, September typically has an average temperature of 18°C (65°F), with highs reaching up to 35°C (96°F) and lows dropping to around 0°C (33°F).
JanFebMarAprMayJunJulAugSepOctNovDec252636465970757265533832
Data source: Temperature data for Lowell 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 Lowell

In Lowell in September, the total precipitation amount is 113 mm (4.5 in) over the course of 10 days.

September Precipitation Trends in Lowell

The chart displays monthly precipitation patterns in Lowell, 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 Lowell, September typically receives around 113 mm (4.5 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec6568658613412068691131306266
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Lowell

In Lowell in September, humidity is 79%. With an average temperature of 18°C (65°F), this humidity feels like walking through a warm mist, making traveling slightly uncomfortable and sticky, but offering a refreshing escape when you find moments of shade or a breeze.

September Average Humidity in Lowell

This chart illustrates the average monthly humidity levels in Lowell, 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 Lowell is approximately 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%87%86%87%82%81%78%79%80%82%87%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Lowell

In Lowell 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 Lowell.

Maximum UV Index Levels in Lowell for September

The chart shows the monthly maximum UV Index (UVI) for Lowell 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 Lowell typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec24589101097532
Data source: Lowell 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 Lowell Compares to Other Months

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

This table compares monthly weather conditions in Lowell, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-4°C (26°F)64 mm (2.5 inches)87%low
February Weather-3°C (27°F)68 mm (2.7 inches)87%moderate
March Weather2°C (37°F)65 mm (2.6 inches)86%moderate
April Weather8°C (46°F)86 mm (3.4 inches)87%very high
May Weather15°C (60°F)134 mm (5.3 inches)82%very high
June Weather21°C (70°F)120 mm (4.7 inches)81%very high
July Weather24°C (75°F)68 mm (2.7 inches)78%very high
August Weather22°C (72°F)69 mm (2.7 inches)79%very high
September Weather18°C (65°F)113 mm (4.5 inches)79%high
October Weather11°C (53°F)130 mm (5.1 inches)82%moderate
November Weather3°C (38°F)62 mm (2.4 inches)87%moderate
December Weather0°C (32°F)65 mm (2.6 inches)86%low

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