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September Weather in Crystal Lakes, United States

Last updated: June 24, 2025

In September, the average temperature in Crystal Lakes, United States hovers around 21°C (69°F). However, be prepared for temperature fluctuations, as it can dip to a cool 5°C (41°F) or soar up to a sizzling 34°C (94°F). During this period, expect about 86 mm (3.4 in) of precipitation spread across 8 days, contributing to an average humidity of 73%.

September Temperature in Crystal Lakes

In September in Crystal Lakes, the average temperature is 21°C (69°F), with maximums reaching 34°C (94°F) and minimums dropping as low as 5°C (41°F). This makes it a great time for travelers to enjoy a variety of outdoor activities while being prepared for some temperature fluctuations.

September Weather in Crystal Lakes: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Crystal Lakes, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Crystal Lakes, September typically has an average temperature of 21°C (69°F), with highs reaching up to 34°C (94°F) and lows dropping to around 5°C (41°F).
JanFebMarAprMayJunJulAugSepOctNovDec303342526472767369574236
Data source: Temperature data for Crystal Lakes 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 Crystal Lakes

In Crystal Lakes in September, the precipitation amount reaches 86 mm (3.4 in) over the course of 8 days.

September Precipitation Trends in Crystal Lakes

The chart displays monthly precipitation patterns in Crystal Lakes, 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 Crystal Lakes, September typically receives around 86 mm (3.4 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec75103105100125122968786999592
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Crystal Lakes

In Crystal Lakes in September, humidity is 73%. With an average temperature of 21°C (69°F), this humidity feels like a warm, sticky embrace, making outdoor activities somewhat stifling and travel a bit more challenging, as the air is dense and can leave you feeling fatigued more quickly.

September Average Humidity in Crystal Lakes

This chart illustrates the average monthly humidity levels in Crystal Lakes, 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 Crystal Lakes is approximately 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%88%87%85%81%82%81%73%73%78%89%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Crystal Lakes

In Crystal Lakes 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 Crystal Lakes.

Maximum UV Index Levels in Crystal Lakes for September

The chart shows the monthly maximum UV Index (UVI) for Crystal Lakes 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 Crystal Lakes typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098643
Data source: Crystal Lakes 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 Crystal Lakes Compares to Other Months

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

This table compares monthly weather conditions in Crystal Lakes, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (31°F)75 mm (3.0 inches)88%moderate
February Weather1°C (34°F)103 mm (4.1 inches)88%moderate
March Weather6°C (42°F)105 mm (4.1 inches)87%high
April Weather11°C (52°F)100 mm (4.0 inches)85%very high
May Weather18°C (64°F)125 mm (4.9 inches)81%very high
June Weather22°C (72°F)122 mm (4.8 inches)82%very high
July Weather24°C (76°F)96 mm (3.8 inches)81%very high
August Weather23°C (74°F)87 mm (3.4 inches)73%very high
September Weather21°C (69°F)86 mm (3.4 inches)73%very high
October Weather14°C (58°F)99 mm (3.9 inches)78%high
November Weather5°C (42°F)95 mm (3.7 inches)89%moderate
December Weather2°C (36°F)92 mm (3.6 inches)87%moderate

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