Climate and Average Weather Year Round in Fairbury Illinois, United States
In Fairbury, the summers are long, warm, humid, and wet; the winters are freezing, snowy, and windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 19°F to 85°F and is rarely below 0°F or above 93°F.
Based on the tourism score, the best time of year to visit Fairbury for warm-weather activities is from early June to mid September.
Climate in Fairbury
The warm season lasts for 4.2 months, from May 17 to September 24, with an average daily high temperature above 75°F. The hottest month of the year in Fairbury is July, with an average high of 85°F and low of 65°F.
The cold season lasts for 3.0 months, from December 2 to March 1, with an average daily high temperature below 44°F. The coldest month of the year in Fairbury is January, with an average low of 20°F and high of 34°F.
Average High and Low Temperature in Fairbury
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, 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 Fairbury
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
Lakkha Nëvre, Russia (5,944 miles away); Uzgen, Kyrgyzstan (6,697 miles); and Seongnam-si, South Korea (6,590 miles) are the far-away foreign places with temperatures most similar to Fairbury (view comparison).
In Fairbury, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Fairbury begins around June 14 and lasts for 4.4 months, ending around October 28.
The clearest month of the year in Fairbury is August, during which on average the sky is clear, mostly clear, or partly cloudy 68% of the time.
The cloudier part of the year begins around October 28 and lasts for 7.6 months, ending around June 14.
The cloudiest month of the year in Fairbury is December, during which on average the sky is overcast or mostly cloudy 56% of the time.
Cloud Cover Categories in Fairbury
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. The chance of wet days in Fairbury varies throughout the year.
The wetter season lasts 5.8 months, from March 27 to September 21, with a greater than 27% chance of a given day being a wet day. The month with the most wet days in Fairbury is June, with an average of 11.5 days with at least 0.04 inches of precipitation.
The drier season lasts 6.2 months, from September 21 to March 27. The month with the fewest wet days in Fairbury is January, with an average of 4.9 days with at least 0.04 inches of precipitation.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Fairbury is June, with an average of 11.5 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 40% on June 7.
Daily Chance of Precipitation in Fairbury
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Fairbury experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Fairbury. The month with the most rain in Fairbury is June, with an average rainfall of 3.7 inches.
The month with the least rain in Fairbury is January, with an average rainfall of 1.0 inches.
Average Monthly Rainfall in Fairbury
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Fairbury experiences some seasonal variation in monthly snowfall.
The snowy period of the year lasts for 3.9 months, from November 24 to March 21, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Fairbury is January, with an average snowfall of 3.5 inches.
The snowless period of the year lasts for 8.1 months, from March 21 to November 24. The least snow falls around July 22, with an average total accumulation of 0.0 inches.
Average Monthly Snowfall in Fairbury
The length of the day in Fairbury varies significantly over the course of the year. In 2023, the shortest day is December 21, with 9 hours, 15 minutes of daylight; the longest day is June 21, with 15 hours, 6 minutes of daylight.
Hours of Daylight and Twilight in Fairbury
The earliest sunrise is at 5:22 AM on June 14, and the latest sunrise is 2 hours, 6 minutes later at 7:27 AM on November 4. The earliest sunset is at 4:26 PM on December 8, and the latest sunset is 4 hours, 3 minutes later at 8:29 PM on June 28.
Daylight saving time (DST) is observed in Fairbury during 2023, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time in Fairbury
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.
Solar Elevation and Azimuth in Fairbury
The figure below presents a compact representation of key lunar data for 2023. 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.
Moon Rise, Set & Phases in Fairbury
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.
Fairbury experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 3.8 months, from May 27 to September 19, during which time the comfort level is muggy, oppressive, or miserable at least 15% of the time. The month with the most muggy days in Fairbury is July, with 17.8 days that are muggy or worse.
The month with the fewest muggy days in Fairbury is January, with 0.0 days that are muggy or worse.
Humidity Comfort Levels in Fairbury
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 Fairbury experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 7.6 months, from October 8 to May 27, with average wind speeds of more than 10.0 miles per hour. The windiest month of the year in Fairbury is March, with an average hourly wind speed of 12.5 miles per hour.
The calmer time of year lasts for 4.4 months, from May 27 to October 8. The calmest month of the year in Fairbury is August, with an average hourly wind speed of 7.5 miles per hour.
Average Wind Speed in Fairbury
The predominant average hourly wind direction in Fairbury varies throughout the year.
The wind is most often from the south for 8.0 months, from March 29 to November 28, with a peak percentage of 37% on November 10. The wind is most often from the west for 4.0 months, from November 28 to March 29, with a peak percentage of 40% on January 1.
Wind Direction in Fairbury
To characterize how pleasant the weather is in Fairbury throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Fairbury for general outdoor tourist activities is from early June to mid September, with a peak score in the last week of August.
Tourism Score in Fairbury
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Fairbury for hot-weather activities is from late June to late August, with a peak score in the third week of July.
Beach/Pool Score in Fairbury
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
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 Fairbury typically lasts for 6.0 months (185 days), from around April 15 to around October 16, rarely starting before March 29 or after May 3, and rarely ending before September 28 or after November 3.
Time Spent in Various Temperature Bands and the Growing Season in Fairbury
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.
Based on growing degree days alone, the first spring blooms in Fairbury should appear around April 4, only rarely appearing before March 21 or after April 20.
Growing Degree Days in Fairbury
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 experiences extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 3.8 months, from May 1 to August 26, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest month of the year in Fairbury is July, with an average of 6.7 kWh.
The darker period of the year lasts for 3.2 months, from November 4 to February 10, with an average daily incident shortwave energy per square meter below 2.8 kWh. The darkest month of the year in Fairbury is December, with an average of 1.8 kWh.
Average Daily Incident Shortwave Solar Energy in Fairbury
For the purposes of this report, the geographical coordinates of Fairbury are 40.747 deg latitude, -88.515 deg longitude, and 682 ft elevation.
The topography within 2 miles of Fairbury is essentially flat, with a maximum elevation change of 56 feet and an average elevation above sea level of 678 feet. Within 10 miles is essentially flat (187 feet). Within 50 miles contains only modest variations in elevation (581 feet).
The area within 2 miles of Fairbury is covered by cropland (88%), within 10 miles by cropland (99%), and within 50 miles by cropland (94%).
This report illustrates the typical weather in Fairbury, 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 Fairbury.
For each station, the records are corrected for the elevation difference between that station and Fairbury 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 Fairbury is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Fairbury and a given station.
The stations contributing to this reconstruction are:
To get a sense of how much these sources agree with each other, you can view a comparison of Fairbury and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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 airports and weather stations are provided by AskGeo.com .
Maps are © OpenStreetMap contributors.
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.
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