Average Weather in Hartford Illinois, United States
In Hartford, the summers are hot and muggy, the winters are very cold and windy, and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 24°F to 88°F and is rarely below 8°F or above 96°F.
Based on the tourism score, the best time of year to visit Hartford for warm-weather activities is from late May to late September.
The hot season lasts for 3.8 months, from May 25 to September 20, with an average daily high temperature above 79°F. The hottest day of the year is July 21, with an average high of 88°F and low of 70°F.
The cold season lasts for 3.0 months, from November 29 to February 27, with an average daily high temperature below 50°F. The coldest day of the year is January 22, with an average low of 24°F and high of 40°F.
Average High and Low Temperature
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 Hartford, 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 Hartford begins around June 13 and lasts for 4.5 months, ending around October 27. On August 26, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 71% of the time, and overcast or mostly cloudy 29% of the time.
The cloudier part of the year begins around October 27 and lasts for 7.5 months, ending around June 13. On February 12, the cloudiest day of the year, the sky is overcast or mostly cloudy 54% of the time, and clear, mostly clear, or partly cloudy 46% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Hartford varies throughout the year.
The wetter season lasts 5.6 months, from March 20 to September 7, with a greater than 28% chance of a given day being a wet day. The chance of a wet day peaks at 40% on May 12.
The drier season lasts 6.4 months, from September 7 to March 20. The smallest chance of a wet day is 16% on January 28.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 40% on May 12.
Daily Chance of Precipitation
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. Hartford experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Hartford. The most rain falls during the 31 days centered around May 13, with an average total accumulation of 4.1 inches.
The least rain falls around January 24, with an average total accumulation of 1.5 inches.
Average Monthly Rainfall
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. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Hartford experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 3.5 months, from November 30 to March 15, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 26, with an average total liquid-equivalent accumulation of 0.3 inches.
The snowless period of the year lasts for 8.5 months, from March 15 to November 30. The least snow falls around July 24, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Hartford varies significantly over the course of the year. In 2018, the shortest day is December 21, with 9 hours, 27 minutes of daylight; the longest day is June 21, with 14 hours, 54 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:34 AM on June 14, and the latest sunrise is 1 hour, 55 minutes later at 7:29 AM on November 3. The earliest sunset is at 4:38 PM on December 7, and the latest sunset is 3 hours, 51 minutes later at 8:29 PM on June 28.
Daylight saving time (DST) is observed in Hartford during 2018, starting in the spring on March 11, lasting 7.8 months, and ending in the fall on November 4.
Sunrise & Sunset with Twilight and Daylight Saving Time
Hartford experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 4.2 months, from May 18 to September 24, during which time the comfort level is muggy, oppressive, or miserable at least 18% of the time. The muggiest day of the year is July 23, with muggy conditions 71% of the time.
The least muggy day of the year is January 28, when muggy conditions are essentially unheard of.
Humidity Comfort Levels
The average hourly wind speed in Hartford experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 7.3 months, from October 12 to May 20, with average wind speeds of more than 8.6 miles per hour. The windiest day of the year is April 1, with an average hourly wind speed of 10.9 miles per hour.
The calmer time of year lasts for 4.7 months, from May 20 to October 12. The calmest day of the year is July 31, with an average hourly wind speed of 6.2 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Hartford varies throughout the year.
The wind is most often from the south for 1.9 weeks, from February 20 to March 5 and for 9.4 months, from March 11 to December 22, with a peak percentage of 43% on June 22. The wind is most often from the north for 6.0 days, from March 5 to March 11, with a peak percentage of 29% on March 8. The wind is most often from the west for 1.9 months, from December 22 to February 20, with a peak percentage of 34% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Hartford 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 Hartford for general outdoor tourist activities is from late May to late September, with a peak score in the first week of September.
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 Hartford for hot-weather activities is from mid June to late August, with a peak score in the last week of July.
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.
The growing season in Hartford typically lasts for 6.9 months (211 days), from around April 2 to around October 30, rarely starting before March 15 or after April 20, and rarely ending before October 12 or after November 16.
Time Spent in Various Temperature Bands and the Growing Season
Based on growing degree days alone, the first spring blooms in Hartford should appear around March 19, only rarely appearing before March 5 or after April 6.
Growing Degree Days
The average daily incident shortwave solar energy experiences significant seasonal variation over the course of the year.
The brighter period of the year lasts for 4.1 months, from April 26 to August 29, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest day of the year is July 2, with an average of 6.8 kWh.
The darker period of the year lasts for 3.1 months, from November 6 to February 9, with an average daily incident shortwave energy per square meter below 3.0 kWh. The darkest day of the year is December 23, with an average of 2.0 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Hartford are 38.833 deg latitude, -90.096 deg longitude, and 423 ft elevation.
The topography within 2 miles of Hartford is essentially flat, with a maximum elevation change of 46 feet and an average elevation above sea level of 421 feet. Within 10 miles is essentially flat (348 feet). Within 50 miles contains only modest variations in elevation (735 feet).
The area within 2 miles of Hartford is covered by artificial surfaces (44%), cropland (35%), and water (20%), within 10 miles by cropland (46%) and artificial surfaces (33%), and within 50 miles by cropland (62%) and trees (23%).
This report illustrates the typical weather in Hartford, 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 5 weather stations near enough to contribute to our estimation of the temperature and dew point in Hartford.
For each station, the records are corrected for the elevation difference between that station and Hartford 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 Hartford is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Hartford and a given station.
The stations contributing to this reconstruction are: Saint Louis Regional Airport (66%, 7 kilometers, northeast); Lambert–St. Louis International Airport (11%, 26 kilometers, west); Saint Louis Downtown - Parks Airport (9%, 30 kilometers, south); St. Charles, St. Charles County Smartt Airport (8%, 31 kilometers, west); and Flying L Airport (6%, 38 kilometers, southeast).
Time zones for aiports and weather stations are provided by AskGeo.com .