nomadseason

September Weather in Crystal Lake, United States

Last updated: June 24, 2025

In September, the average temperature in Crystal Lake, United States reaches a pleasant 27°C (81°F). Temperatures can vary, with a minimum of 18°C (65°F) and a maximum of 34°C (93°F). Rainfall is prevalent, averaging 186 mm (7.3 in) over 21 days, contributing to an average humidity of 83%. Enjoy the tropical vibes while being prepared for occasional showers!

September Temperature in Crystal Lake

In September in Crystal Lake, the average temperature is 27°C (81°F). Maximums can reach 34°C (93°F), and minimums can be as low as 18°C (65°F). This pleasant climate makes Crystal Lake an ideal destination for outdoor activities and sightseeing during this time of year.

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

The chart illustrates September temperature patterns in Crystal Lake, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Crystal Lake, September typically has an average temperature of 27°C (81°F), with highs reaching up to 34°C (93°F) and lows dropping to around 18°C (65°F).
JanFebMarAprMayJunJulAugSepOctNovDec616769747881818281786964
Data source: Temperature data for Crystal Lake generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Crystal Lake

In Crystal Lake in September, the precipitation amount is 186 mm (7.3 in) during a span of 21 days.

September Precipitation Trends in Crystal Lake

The chart displays monthly precipitation patterns in Crystal Lake, 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 Lake, September typically receives around 186 mm (7.3 inches) of precipitation spread over approximately 21 days.
JanFebMarAprMayJunJulAugSepOctNovDec40601766130222249231186734458
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Crystal Lake

In Crystal Lake in September humidity is 83%. With an average temperature of 27°C (81°F), this humidity feels like a warm blanket enveloping you, making sightseeing and outdoor activities feel more exhausting and requiring frequent breaks to relax in the shade or cool off.

September Average Humidity in Crystal Lake

This chart illustrates the average monthly humidity levels in Crystal Lake, 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 Lake is approximately 83%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec83%80%75%68%65%73%77%80%83%83%83%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Crystal Lake

In Crystal Lake in September, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Crystal Lake.

Maximum UV Index Levels in Crystal Lake for September

The chart shows the monthly maximum UV Index (UVI) for Crystal Lake 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 Lake typically reaches 11, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec6810111112121111975
Data source: Crystal Lake 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 Lake Compares to Other Months

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

This table compares monthly weather conditions in Crystal Lake, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather16°C (62°F)40 mm (1.6 inches)83%high
February Weather20°C (68°F)59 mm (2.3 inches)80%very high
March Weather21°C (69°F)17 mm (0.7 inches)75%very high
April Weather23°C (74°F)66 mm (2.6 inches)68%extreme
May Weather26°C (79°F)130 mm (5.1 inches)65%extreme
June Weather27°C (81°F)222 mm (8.7 inches)73%extreme
July Weather27°C (82°F)249 mm (9.8 inches)77%extreme
August Weather28°C (82°F)231 mm (9.1 inches)80%extreme
September Weather27°C (81°F)186 mm (7.3 inches)83%extreme
October Weather25°C (78°F)73 mm (2.9 inches)83%very high
November Weather21°C (69°F)44 mm (1.7 inches)83%high
December Weather18°C (65°F)58 mm (2.3 inches)84%moderate

Compare Crystal Lake's Climate with Cities Worldwide