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September Weather in Norwalk, United States

Last updated: June 24, 2025

In September, the average temperature in Norwalk, United States is a pleasant 20°C (69°F). Visitors can expect a minimum temperature around 5°C (42°F) and a maximum of 34°C (93°F). During this time, 112 mm (4.4 in) of precipitation is typical, spread over 9 days, contributing to an average humidity of 73%.

September Temperature in Norwalk

In September in Norwalk, the average temperature is 20°C (69°F). Maximum temperatures can reach 34°C (93°F), while minimums can drop as low as 5°C (42°F). This makes it a great time to explore outdoor attractions, but travelers should be prepared for both warm and cool weather.

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

The chart illustrates September temperature patterns in Norwalk, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Norwalk, September typically has an average temperature of 20°C (69°F), with highs reaching up to 34°C (93°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec232440506275777469533931
Data source: Temperature data for Norwalk 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 Norwalk

In Norwalk in September, the total precipitation amount is 112 mm (4.4 in), occurring over a span of 9 days.

September Precipitation Trends in Norwalk

The chart displays monthly precipitation patterns in Norwalk, 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 Norwalk, September typically receives around 112 mm (4.4 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec3840837217112267821121263937
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Norwalk

In Norwalk in September humidity is 73%. With an average temperature of 20°C (69°F), this humidity feels like a warm embrace, making travel slightly sticky but ultimately comfortable as long as you stay hydrated and take breaks in the shade.

September Average Humidity in Norwalk

This chart illustrates the average monthly humidity levels in Norwalk, 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 Norwalk is approximately 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec78%80%77%78%77%81%81%77%73%75%85%83%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Norwalk

In Norwalk 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 Norwalk.

Maximum UV Index Levels in Norwalk for September

The chart shows the monthly maximum UV Index (UVI) for Norwalk 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 Norwalk typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec35689111098643
Data source: Norwalk 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 Norwalk Compares to Other Months

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

This table compares monthly weather conditions in Norwalk, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (23°F)38 mm (1.5 inches)78%moderate
February Weather-4°C (24°F)40 mm (1.6 inches)80%moderate
March Weather4°C (40°F)83 mm (3.3 inches)77%high
April Weather10°C (50°F)72 mm (2.9 inches)77%very high
May Weather17°C (63°F)171 mm (6.7 inches)77%very high
June Weather24°C (75°F)122 mm (4.8 inches)81%extreme
July Weather25°C (78°F)67 mm (2.6 inches)81%very high
August Weather24°C (75°F)82 mm (3.2 inches)77%very high
September Weather20°C (69°F)112 mm (4.4 inches)73%very high
October Weather11°C (53°F)126 mm (4.9 inches)75%high
November Weather4°C (39°F)39 mm (1.5 inches)85%moderate
December Weather0°C (31°F)37 mm (1.5 inches)83%moderate

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