Fall Weather in Crystal Lake Illinois, United States

Daily high temperatures decrease by 38°F, from 78°F to 40°F, rarely falling below 27°F or exceeding 87°F.

Daily low temperatures decrease by 33°F, from 59°F to 26°F, rarely falling below 11°F or exceeding 68°F.

For reference, on July 18, the hottest day of the year, temperatures in Crystal Lake typically range from 64°F to 83°F, while on January 22, the coldest day of the year, they range from 15°F to 29°F.

The figure below shows you a compact characterization of the hourly average fall temperatures. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Garrni, Armenia (6,040 miles away) is the far-away foreign place with temperatures most similar to Crystal Lake (view comparison).

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The fall in Crystal Lake experiences very rapidly increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 33% to 55%.

The clearest day of the fall is September 14, with clear, mostly clear, or partly cloudy conditions 68% of the time.

For reference, on December 30, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 58%, while on August 25, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 68%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Crystal Lake, the chance of a wet day over the course of the fall is very rapidly decreasing, starting the season at 30% and ending it at 22%.

For reference, the year's highest daily chance of a wet day is 38% on May 23, and its lowest chance is 14% on February 2.

Over the course of the fall in Crystal Lake, the chance of a day with only rain decreases from 30% to 15%, the chance of a day with mixed snow and rain increases from 0% to 4%, and the chance of a day with only snow increases from 0% to 4%.

Rainfall

To show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during the fall in Crystal Lake is rapidly decreasing, starting the season at 3.3 inches, when it rarely exceeds 5.9 inches or falls below 1.2 inches, and ending the season at 1.7 inches, when it rarely exceeds 3.2 inches or falls below 0.4 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day snowfall during the fall in Crystal Lake is rapidly increasing, starting the season at 0.0 inches, when it rarely exceeds 0.0 inches, and ending the season at 3.2 inches, when it rarely exceeds 9.1 inches.

Over the course of the fall in Crystal Lake, the length of the day is very rapidly decreasing. From the start to the end of the season, the length of the day decreases by 3 hours, 47 minutes, implying an average daily decrease of 2 minutes, 31 seconds, and weekly decrease of 17 minutes, 38 seconds.

The shortest day of the fall is November 30, with 9 hours, 20 minutes of daylight and the longest day is September 1, with 13 hours, 7 minutes of daylight.

The earliest sunrise of the fall in Crystal Lake is 6:19 AM on September 1 and the latest sunrise is 1 hour, 9 minutes later at 7:28 AM on November 2.

The latest sunset is 7:26 PM on September 1 and the earliest sunset is 3 hours, 4 minutes earlier at 4:22 PM on November 30.

Daylight saving time (DST) ends at 1:00 AM on November 3, 2024, shifting sunrise and sunset to be an hour earlier.

For reference, on June 20, the longest day of the year, the Sun rises at 5:16 AM and sets 15 hours, 16 minutes later, at 8:33 PM, while on December 21, the shortest day of the year, it rises at 7:19 AM and sets 9 hours, 5 minutes later, at 4:24 PM.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

The figure below presents a compact representation of key lunar data for the fall of 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The chance that a given day will be muggy in Crystal Lake is very rapidly decreasing during the fall, falling from 25% to 0% over the course of the season.

For reference, on July 21, the muggiest day of the year, there are muggy conditions 40% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Crystal Lake is rapidly increasing during the fall, increasing from 8.6 miles per hour to 11.9 miles per hour over the course of the season.

For reference, on January 15, the windiest day of the year, the daily average wind speed is 12.7 miles per hour, while on August 2, the calmest day of the year, the daily average wind speed is 7.9 miles per hour.

The wind direction in Crystal Lake during the fall is predominantly out of the south from September 1 to October 15 and from November 4 to November 12 and the west from October 15 to November 4 and from November 12 to November 30.

Crystal Lake is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average surface water temperature in Crystal Lake is very rapidly decreasing during the fall, falling by 26°F, from 70°F to 44°F, over the course of the season.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Crystal Lake typically lasts for 5.5 months (168 days), from around April 26 to around October 11, rarely starting before April 8 or after May 14, and rarely ending before September 23 or after October 28.

During the fall in Crystal Lake, the chance that a given day is within the growing season is very rapidly decreasing falling from 100% to -0% over the course of the season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average accumulated growing degree days in Crystal Lake are rapidly increasing during the fall, increasing by 576°F, from 2,372°F to 2,948°F, over the course of the season.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy in Crystal Lake is very rapidly decreasing during the fall, falling by 3.7 kWh, from 5.5 kWh to 1.8 kWh, over the course of the season.

For the purposes of this report, the geographical coordinates of Crystal Lake are 42.241 deg latitude, -88.316 deg longitude, and 912 ft elevation.

The topography within 2 miles of Crystal Lake contains only modest variations in elevation, with a maximum elevation change of 135 feet and an average elevation above sea level of 901 feet. Within 10 miles also contains only modest variations in elevation (308 feet). Within 50 miles contains only modest variations in elevation (745 feet).

The area within 2 miles of Crystal Lake is covered by artificial surfaces (80%) and trees (11%), within 10 miles by cropland (41%) and artificial surfaces (36%), and within 50 miles by cropland (51%) and artificial surfaces (25%).