Climate and Average Weather Year Round in Edwardsville Illinois, United States

In Edwardsville, the summers are warm and muggy; the winters are very cold, snowy, 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 95°F.

Based on the tourism score, the best time of year to visit Edwardsville for warm-weather activities is from late May to late September.

The hot season lasts for 3.9 months, from May 25 to September 20, with an average daily high temperature above 78°F. The hottest month of the year in Edwardsville is July, with an average high of 88°F and low of 68°F.

The cold season lasts for 3.0 months, from November 29 to February 28, with an average daily high temperature below 49°F. The coldest month of the year in Edwardsville is January, with an average low of 24°F and high of 40°F.

In Edwardsville, 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 Edwardsville begins around June 14 and lasts for 4.5 months, ending around October 29.

The clearest month of the year in Edwardsville is August, during which on average the sky is clear, mostly clear, or partly cloudy 69% of the time.

The cloudier part of the year begins around October 29 and lasts for 7.5 months, ending around June 14.

The cloudiest month of the year in Edwardsville is February, during which on average the sky is overcast or mostly cloudy 53% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Edwardsville varies throughout the year.

The wetter season lasts 5.3 months, from March 23 to August 31, with a greater than 28% chance of a given day being a wet day. The month with the most wet days in Edwardsville is May, with an average of 12.0 days with at least 0.04 inches of precipitation.

The drier season lasts 6.7 months, from August 31 to March 23. The month with the fewest wet days in Edwardsville is January, with an average of 5.2 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 Edwardsville is May, with an average of 12.0 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.

Rainfall

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. Edwardsville experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year in Edwardsville. The month with the most rain in Edwardsville is May, with an average rainfall of 4.1 inches.

The month with the least rain in Edwardsville is January, with an average rainfall of 1.6 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Edwardsville experiences some seasonal variation in monthly snowfall.

The snowy period of the year lasts for 3.6 months, from November 29 to March 16, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Edwardsville is January, with an average snowfall of 3.5 inches.

The snowless period of the year lasts for 8.4 months, from March 16 to November 29. The least snow falls around July 24, with an average total accumulation of 0.0 inches.

The length of the day in Edwardsville varies significantly over the course of the year. In 2023, the shortest day is December 21, with 9 hours, 27 minutes of daylight; the longest day is June 21, with 14 hours, 53 minutes of daylight.

The earliest sunrise is at 5:34 AM on June 14, and the latest sunrise is 1 hour, 56 minutes later at 7:29 AM on November 4. The earliest sunset is at 4:37 PM on December 8, and the latest sunset is 3 hours, 51 minutes later at 8:29 PM on June 28.

Daylight saving time (DST) is observed in Edwardsville during 2023, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

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.

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.

Edwardsville 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 month with the most muggy days in Edwardsville is July, with 21.3 days that are muggy or worse.

The month with the fewest muggy days in Edwardsville is January, with 0.0 days that are muggy or worse.

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 Edwardsville experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 7.3 months, from October 11 to May 21, with average wind speeds of more than 8.8 miles per hour. The windiest month of the year in Edwardsville is March, with an average hourly wind speed of 11.0 miles per hour.

The calmer time of year lasts for 4.7 months, from May 21 to October 11. The calmest month of the year in Edwardsville is August, with an average hourly wind speed of 6.6 miles per hour.

The predominant average hourly wind direction in Edwardsville varies throughout the year.

The wind is most often from the south for 2.0 weeks, from February 19 to March 5 and for 9.4 months, from March 12 to December 23, with a peak percentage of 43% on June 22. The wind is most often from the north for 1.0 weeks, from March 5 to March 12, with a peak percentage of 30% on March 8. The wind is most often from the west for 1.9 months, from December 23 to February 19, with a peak percentage of 33% on January 1.

To characterize how pleasant the weather is in Edwardsville 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 Edwardsville for general outdoor tourist activities is from late May to late September, with a peak score in the last week of August.

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 Edwardsville for hot-weather activities is from mid June to late August, with a peak score in the last week of July.

Methodology

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 Edwardsville typically lasts for 6.7 months (205 days), from around April 5 to around October 27, rarely starting before March 17 or after April 22, and rarely ending before October 8 or after November 14.

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 Edwardsville should appear around March 20, only rarely appearing before March 6 or after April 6.

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 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 month of the year in Edwardsville is July, with an average of 6.7 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 month of the year in Edwardsville is December, with an average of 2.1 kWh.

For the purposes of this report, the geographical coordinates of Edwardsville are 38.811 deg latitude, -89.953 deg longitude, and 538 ft elevation.

The topography within 2 miles of Edwardsville contains only modest variations in elevation, with a maximum elevation change of 157 feet and an average elevation above sea level of 510 feet. Within 10 miles also contains only modest variations in elevation (210 feet). Within 50 miles contains only modest variations in elevation (715 feet).

The area within 2 miles of Edwardsville is covered by artificial surfaces (41%), trees (38%), and cropland (22%), within 10 miles by cropland (65%) and artificial surfaces (20%), and within 50 miles by cropland (66%) and trees (19%).