So far August has been cooler than normal. And that is likely to continue for a while. Here are the temperature departures for August so far. The statewide average temperature for Illinois is running about 2 degrees below the 1981-2010 normal.
As a cold front swept through Illinois yesterday and today, it has brought cooler and less humid air behind it. And according to the National Weather Service, those cooler temperatures will be around awhile. Over the next 7 days, highs will range from the low 70s in northern Illinois to the mid to upper 70s in central Illinois and the upper 70s and low 80s in southern Illinois. That’s about 6 degrees below normal for this time of year.
Here are the daily temperature departures for the summer of 2017 from the long-term daily normals for three sites in Illinois – Chicago, Champaign, and Carbondale.
Chicago experienced an early summer heat wave in the first two weeks of June with temperatures reaching up into the 90s, which was well above normal for that time of year. This was followed by cooler conditions in the second half of June. Periods of cooler and warmer than normal weather alternating throughout July, which is pretty common. August has been running cooler than normal so far. The lesson here is that early season heat waves do not necessarily set the tone for the rest of the summer (thank goodness). For Chicago, June was 3.5 degrees above normal, July was 0.6 degrees above normal, and August so far is 2.5 degrees below normal. Continue reading
So far, August has been about 4 degrees below normal and dry across the state.
Here are the precipitation maps for the Midwest for August – more rains across the northern and southern most parts of the Midwest. Meanwhile, the rains mostly missed the central Midwest, especially in northern Missouri, eastern Iowa, southwest Wisconsin, and northern Illinois. Click to enlarge.
Summary: There is a big shift in the weather pattern coming to Illinois as a strong cold front moves through Illinois on Friday and Saturday. Behind it will be cooler, less humid air. In fact, cooler temperatures are expected to dominate in Illinois over the next few weeks.
For the weekend and next week, daytime highs will range from the 70s in northern Illinois, the 70s and low 80s in central Illinois, and low 80s in southern Illinois. Overnight lows will range from the mid-50s to low 60s in northern and central Illinois, and in the low to mid-60s in southern Illinois.
There is an old statistics joke about “Stick one foot in the fire and one foot in a bucket of ice, and on average you are at a comfortable temperature”. That happened to precipitation in Illinois in July. Northern Illinois experienced heavy rains and widespread flooding. Meanwhile, parts of central and southern Illinois experienced dry weather that caused crop damage. However, on average the statewide precipitation was 4.81 inches, which is 0.73 inches above normal.
Three of the highest monthly totals for July in Illinois were Cary (McHenry County) with 13.34 inches, Gurnee (Lake County) with 13.21 inches, and Chadwick (Carroll County) with 13.15 inches.