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September Weather in Holtsville, United States

Last updated: June 24, 2025

In Holtsville, United States, the average temperature in September is a pleasant 21°C (70°F). Expect minimums around 12°C (53°F) and maximums soaring to 29°C (84°F). During this time, you can anticipate approximately 91 mm (3.6 in) of precipitation spread over 9 days, with an average humidity hovering around 68%. Perfect for those who enjoy a balanced climate!

September Temperature in Holtsville

In September in Holtsville, the average temperature is 21°C (70°F). Maximums can reach 29°C (84°F), while minimums can drop to as low as 12°C (53°F). This mild climate makes it an ideal destination for travelers looking to explore comfortably.

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

The chart illustrates September temperature patterns in Holtsville, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Holtsville, September typically has an average temperature of 21°C (70°F), with highs reaching up to 29°C (84°F) and lows dropping to around 12°C (53°F).
JanFebMarAprMayJunJulAugSepOctNovDec363740485767757569614941
Data source: Temperature data for Holtsville 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 Holtsville

In Holtsville in September, the precipitation amount is 91 mm (3.6 in) spread over 9 days.

September Precipitation Trends in Holtsville

The chart displays monthly precipitation patterns in Holtsville, 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 Holtsville, September typically receives around 91 mm (3.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec801081061251177711310191137103134
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Holtsville

In Holtsville in September humidity is 68%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making the air feel slightly heavy and sticky, which can be quite exhausting for travelers.

September Average Humidity in Holtsville

This chart illustrates the average monthly humidity levels in Holtsville, 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 Holtsville is approximately 68%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%81%78%70%69%62%65%68%74%82%80%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Holtsville

In Holtsville 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 Holtsville.

Maximum UV Index Levels in Holtsville for September

The chart shows the monthly maximum UV Index (UVI) for Holtsville 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 Holtsville typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356810101098642
Data source: Holtsville 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 Holtsville Compares to Other Months

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

This table compares monthly weather conditions in Holtsville, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather2°C (36°F)80 mm (3.1 inches)84%moderate
February Weather3°C (37°F)108 mm (4.3 inches)82%moderate
March Weather5°C (41°F)106 mm (4.2 inches)81%high
April Weather9°C (49°F)125 mm (4.9 inches)78%very high
May Weather14°C (57°F)117 mm (4.6 inches)69%very high
June Weather20°C (67°F)77 mm (3.0 inches)69%very high
July Weather24°C (75°F)113 mm (4.5 inches)62%very high
August Weather24°C (75°F)101 mm (4.0 inches)65%very high
September Weather21°C (70°F)91 mm (3.6 inches)68%very high
October Weather16°C (62°F)137 mm (5.4 inches)74%high
November Weather10°C (50°F)103 mm (4.1 inches)82%moderate
December Weather5°C (42°F)134 mm (5.3 inches)80%low

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