(12:00PM – 5/27/18) An early season period of heat is currently affecting the state and a good portion of the region, bringing several days with high temperatures into the 90’s for many areas.
On Saturday high temperatures across the state ranged from the mid 80’s to low 90’s. With warming upper level temperatures, good mixing of the atmosphere and clear skies, even hotter temperatures will continue for the next few days. Today (Sunday) high temps will likely be in the mid-90’s across much of Northern and Central Illinois, with upper 80’s to low 90’s expected across Southern Illinois. On Monday high temps will likely be in the mid-upper 90’s across Northern Illinois, with a localized temp around 100 not out of the question. Highs in the low to mid 90’s will be possible across Central Illinois, and upper 80’s to low 90’s in Southern Illinois. By Tuesday the remnants of Tropical Storm Alberto will be moving into the region, which will hold temperatures lower for some areas. Highs in the low 90’s will be likely across Northern Illinois, with high temps likely staying in the 80’s for areas south. Low temps will also stay warm during this period, with lows in the mid 60’s to lower 70’s likely.
Heat index values will be an issue as well. Moderate to high dew points in the mid 60’s to low 70’s, combined with the aforementioned hot temps, will likely cause heat index values to reach 95-103 for many areas. While mixing of the atmosphere will likely prevent things from getting out of hand with higher dew points and temps overlapping, the expected values will still be high.