Average Weather in January in Bunker Hill Illinois, United States
Daily high temperatures are around 39°F, rarely falling below 23°F or exceeding 55°F. The lowest daily average high temperature is 38°F on January 16.
Daily low temperatures are around 24°F, rarely falling below 6°F or exceeding 38°F. The lowest daily average low temperature is 23°F on January 22.
For reference, on July 20, the hottest day of the year, temperatures in Bunker Hill typically range from 68°F to 87°F, while on January 22, the coldest day of the year, they range from 23°F to 38°F.
Average High and Low Temperature in January
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on January. 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 January
Agarak, Armenia (6,377 miles away); Mahdishahr, Iran (6,774 miles); and Osh City, Kyrgyzstan (6,839 miles) are the far-away foreign places with temperatures most similar to Bunker Hill (view comparison).
The month of January in Bunker Hill experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 53% throughout the month.
The clearest day of the month is January 12, with clear, mostly clear, or partly cloudy conditions 48% of the time.
For reference, on February 12, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 55%, while on August 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 70%.
Cloud Cover Categories in January
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 Bunker Hill, the chance of a wet day over the course of January is gradually decreasing, starting the month at 19% and ending it at 16%.
For reference, the year's highest daily chance of a wet day is 40% on June 8, and its lowest chance is 15% on January 28.
Over the course of January in Bunker Hill, the chance of a day with only rain decreases from 13% to 9%, the chance of a day with mixed snow and rain remains an essentially constant 3% throughout, and the chance of a day with only snow remains an essentially constant 4% throughout.
Probability of Precipitation in January
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 January in Bunker Hill is gradually decreasing, starting the month at 1.9 inches, when it rarely exceeds 3.8 inches or falls below 0.2 inches, and ending the month at 1.4 inches, when it rarely exceeds 3.1 inches or falls below 0.2 inches.
The lowest average 31-day accumulation is 1.4 inches on January 24.
Average Monthly Rainfall in January
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 January in Bunker Hill is essentially constant, remaining about 0.4 inches throughout, and rarely exceeding 1.0 inches or falling to 0.0 inches.
The highest average 31-day liquid-equivalent accumulation is 0.4 inches on January 26.
Average Monthly Liquid-Equivalent Snowfall in January
Over the course of January in Bunker Hill, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 43 minutes, implying an average daily increase of 1 minute, 27 seconds, and weekly increase of 10 minutes, 7 seconds.
The shortest day of the month is January 1, with 9 hours, 29 minutes of daylight and the longest day is January 31, with 10 hours, 13 minutes of daylight.
Hours of Daylight and Twilight in January
The latest sunrise of the month in Bunker Hill is 7:19 AM on January 4 and the earliest sunrise is 12 minutes earlier at 7:07 AM on January 31.
The earliest sunset is 4:48 PM on January 1 and the latest sunset is 32 minutes later at 5:19 PM on January 31.
Daylight saving time is observed in Bunker Hill during 2018, but it neither starts nor ends during January, so the entire month is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:34 AM and sets 14 hours, 55 minutes later, at 8:29 PM, while on December 21, the shortest day of the year, it rises at 7:15 AM and sets 9 hours, 25 minutes later, at 4:40 PM.
Sunrise & Sunset with Twilight in January
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 Bunker Hill is essentially constant during January, remaining around 0% throughout.
For reference, on July 22, the muggiest day of the year, there are muggy conditions 68% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in January
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 Bunker Hill is essentially constant during January, remaining within 0.1 miles per hour of 11.1 miles per hour throughout.
For reference, on April 1, the windiest day of the year, the daily average wind speed is 11.8 miles per hour, while on July 31, the calmest day of the year, the daily average wind speed is 6.7 miles per hour.
Average Wind Speed in January
Wind Direction in January
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 Bunker Hill typically lasts for 6.6 months (203 days), from around April 6 to around October 26, rarely starting before March 18 or after April 25, and rarely ending before October 8 or after November 13.
The month of January in Bunker Hill is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in January
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 Bunker Hill are essentially constant during January, remaining within 5°F of 5°F throughout.
Growing Degree Days in January
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 Bunker Hill is gradually increasing during January, rising by 0.6 kWh, from 2.0 kWh to 2.7 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in January
For the purposes of this report, the geographical coordinates of Bunker Hill are 39.043 deg latitude, -89.952 deg longitude, and 630 ft elevation.
The topography within 2 miles of Bunker Hill contains only modest variations in elevation, with a maximum elevation change of 105 feet and an average elevation above sea level of 630 feet. Within 10 miles also contains only modest variations in elevation (259 feet). Within 50 miles contains only modest variations in elevation (735 feet).
The area within 2 miles of Bunker Hill is covered by cropland (79%) and trees (14%), within 10 miles by cropland (68%) and trees (30%), and within 50 miles by cropland (70%) and trees (16%).
This report illustrates the typical weather in Bunker Hill 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Bunker Hill.
For each station, the records are corrected for the elevation difference between that station and Bunker Hill 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 Bunker Hill is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Bunker Hill and a given station.
The stations contributing to this reconstruction are: Saint Louis Regional Airport (58%, 20 kilometers, southwest); Litchfield Municipal Airport (36%, 27 kilometers, northeast); and Jacksonville Municipal Airport (6%, 86 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.