Average Weather in December in Heritage Lake Illinois, United States
Daily high temperatures decrease by 9°F, from 43°F to 34°F, rarely falling below 18°F or exceeding 58°F.
Daily low temperatures decrease by 8°F, from 29°F to 21°F, rarely falling below 2°F or exceeding 42°F.
For reference, on July 19, the hottest day of the year, temperatures in Heritage Lake typically range from 67°F to 85°F, while on January 28, the coldest day of the year, they range from 19°F to 33°F.
Average High and Low Temperature in December
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on December. 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.
Average Hourly Temperature in December
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The month of December in Heritage Lake experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 56% throughout the month. The highest chance of overcast or mostly cloudy conditions is 57% on December 31.
The clearest day of the month is December 2, with clear, mostly clear, or partly cloudy conditions 46% of the time.
For reference, on December 31, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 57%, while on August 27, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 69%.
Cloud Cover Categories in December
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Heritage Lake, the chance of a wet day over the course of December is decreasing, starting the month at 24% and ending it at 19%.
For reference, the year's highest daily chance of a wet day is 39% on June 8, and its lowest chance is 14% on January 29.
Over the course of December in Heritage Lake, the chance of a day with only rain decreases from 18% to 11%, the chance of a day with mixed snow and rain remains an essentially constant 4% throughout, and the chance of a day with only snow increases from 2% to 6%.
Probability of Precipitation in December
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during December in Heritage Lake is decreasing, starting the month at 2.1 inches, when it rarely exceeds 3.8 inches or falls below 0.6 inches, and ending the month at 1.3 inches, when it rarely exceeds 3.0 inches or falls below 0.1 inches.
Average Monthly Rainfall in December
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. As with rainfall, we consider the liquid-equivalent snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day liquid-equivalent snowfall during December in Heritage Lake is essentially constant, remaining about 0.3 inches throughout, and rarely exceeding 1.1 inches or falling below -0.0 inches.
The highest average 31-day liquid-equivalent accumulation is 0.4 inches on December 25.
Average Monthly Liquid-Equivalent Snowfall in December
Over the course of December in Heritage Lake, the length of the day is essentially constant. The shortest day of the month is December 21, with 9 hours, 16 minutes of daylight and the longest day is December 1, with 9 hours, 30 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Heritage Lake is 7:01 AM on December 1 and the latest sunrise is 19 minutes later at 7:20 AM on December 31.
The earliest sunset is 4:30 PM on December 7 and the latest sunset is 10 minutes later at 4:40 PM on December 31.
Daylight saving time is observed in Heritage Lake during 2019, but it neither starts nor ends during December, so the entire month is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:26 AM and sets 15 hours, 5 minutes later, at 8:31 PM, while on December 22, the shortest day of the year, it rises at 7:17 AM and sets 9 hours, 16 minutes later, at 4:33 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
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 Heritage Lake is essentially constant during December, remaining around 0% throughout.
For reference, on July 22, the muggiest day of the year, there are muggy conditions 58% of the time, while on December 13, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in December
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Heritage Lake is essentially constant during December, remaining within 0.2 miles per hour of 11.5 miles per hour throughout.
For reference, on April 1, the windiest day of the year, the daily average wind speed is 12.7 miles per hour, while on August 3, the calmest day of the year, the daily average wind speed is 7.4 miles per hour.
Average Wind Speed in December
The wind direction in Heritage Lake during December is predominantly out of the south from December 1 to December 3 and the west from December 3 to December 31.
Wind Direction in December
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 Heritage Lake typically lasts for 6.3 months (193 days), from around April 12 to around October 23, rarely starting before March 27 or after April 30, and rarely ending before October 3 or after November 12.
The month of December in Heritage Lake is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in December
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
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 Heritage Lake are essentially constant during December, remaining within 5°F of 3,551°F throughout.
Growing Degree Days in December
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 Heritage Lake is essentially constant during December, remaining within 0.1 kWh of 1.9 kWh throughout.
The lowest average daily incident shortwave solar energy during December is 1.8 kWh on December 17.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Heritage Lake are 40.547 deg latitude, -89.326 deg longitude, and 689 ft elevation.
The topography within 2 miles of Heritage Lake contains only modest variations in elevation, with a maximum elevation change of 230 feet and an average elevation above sea level of 682 feet. Within 10 miles also contains only modest variations in elevation (338 feet). Within 50 miles contains only modest variations in elevation (535 feet).
The area within 2 miles of Heritage Lake is covered by cropland (63%) and trees (32%), within 10 miles by cropland (92%), and within 50 miles by cropland (89%).
This report illustrates the typical weather in Heritage Lake year round, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Heritage Lake.
For each station, the records are corrected for the elevation difference between that station and Heritage Lake according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Heritage Lake is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Heritage Lake and a given station.
The stations contributing to this reconstruction are: Central Illinois Regional Airport at Bloomington-Normal (32%, 33 kilometers, east); General Downing - Peoria International Airport (32%, 33 kilometers, northwest); Logan County Airport (21%, 43 kilometers, south); and Marshall County Airport (16%, 53 kilometers, north).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.