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September Weather in Union, United States

Last updated: June 24, 2025

In Union, United States, the average temperature in September hovers around 25°C (78°F). However, be prepared for a range, as temperatures can dip to a minimum of 11°C (53°F) and soar to a maximum of 38°C (101°F). Expect about 95 mm (3.8 in) of precipitation over roughly 9 days, with an average humidity of 74%.

September Temperature in Union

In September in Union, the average temperature is 25°C (78°F), with maximums reaching up to 38°C (101°F) and minimums dropping as low as 11°C (53°F). This makes Union an ideal destination for travelers seeking pleasant warm weather during this time.

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

The chart illustrates September temperature patterns in Union, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Union, September typically has an average temperature of 25°C (78°F), with highs reaching up to 38°C (101°F) and lows dropping to around 11°C (53°F).
JanFebMarAprMayJunJulAugSepOctNovDec485460647379818178695551
Data source: Temperature data for Union 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 Union

In Union in September, the total precipitation amount is 95 mm (3.8 in) over the course of 9 days.

September Precipitation Trends in Union

The chart displays monthly precipitation patterns in Union, 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 Union, September typically receives around 95 mm (3.8 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec1051561161361221631211279610070121
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Union

In Union in September humidity is 74%. With an average temperature of 25°C (78°F), this humidity feels like you're enveloped in a warm, thick blanket, making outdoor activities feel more strenuous and necessitating frequent breaks and hydration for comfortable travel.

September Average Humidity in Union

This chart illustrates the average monthly humidity levels in Union, 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 Union is approximately 74%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%84%82%82%82%79%82%77%74%73%85%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Union

In Union in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Union.

Maximum UV Index Levels in Union for September

The chart shows the monthly maximum UV Index (UVI) for Union 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 Union typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec478111111111110864
Data source: Union 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 Union Compares to Other Months

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

This table compares monthly weather conditions in Union, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather9°C (48°F)105 mm (4.1 inches)85%moderate
February Weather12°C (54°F)156 mm (6.1 inches)84%high
March Weather16°C (60°F)116 mm (4.6 inches)82%very high
April Weather18°C (65°F)136 mm (5.4 inches)82%extreme
May Weather23°C (74°F)122 mm (4.8 inches)82%extreme
June Weather26°C (79°F)163 mm (6.4 inches)79%extreme
July Weather27°C (81°F)121 mm (4.8 inches)82%extreme
August Weather27°C (81°F)127 mm (5.0 inches)77%extreme
September Weather25°C (78°F)95 mm (3.8 inches)74%very high
October Weather20°C (69°F)100 mm (3.9 inches)73%very high
November Weather13°C (55°F)70 mm (2.7 inches)85%high
December Weather11°C (52°F)121 mm (4.8 inches)88%moderate

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