Mid-July Heat Wave Update #9

​(6:00PM - 7/21/20) The heat wave that has been affecting portions of the state and region over the past week or so is steadily winding down, with only lingering affecting expected across Southern Illinois through Thursday.

Summary....
A heat wave has been affecting portions of the state for the past week or so, and now steadily winding down. The most consistently hot temperatures and humid conditions during this period have been across Southern Illinois. Across Northern and Central Illinois, the hottest temperatures and most humid conditions were this past weekend, as the ridge flexed northward for a time. Additionally, an active storm pattern has been in place, which tempered the heat at times for many areas. Through Thursday,  high temperatures in the mid 80's to low 90's will occur on a daily basis across Southern Illinois, with somewhat cooler temperatures across Northern and Central Illinois. Low temperatures in the low 60's to low 70's will be likely on a nightly basis across the state. High humidity and heat indices will continue to be likely across Southern Illinois as well, with heat index values in the low to upper 90's likely on a daily basis. Heat index values across Northern and Central Illinois will be more tolerable, in the low to upper 80's.

​An update will be provided each day for the duration of this heat wave across the state. Each update will feature a recap of previous days temperatures, along with the forecast for the next two days, and any other overall additional information.

Forecast For Next Two Days...
Wednesday, July 22nd Forecast...
High temperatures will range from the mid 80's to low 90's across Southern Illinois, to the upper 70's to mid 80's across Northern and Central Illinois. Heat index values in the mid 80's to mid 90's across Southern Illinois. Low temperatures in the low 60's to low 70's across the state. Periods of scattered showers and t'storms will be possible across Southern Illinois at times as a "cold" front continues to sweep across the state, tempering the heat for some areas.

Thursday, July 23rd Forecast...
High temperatures will range from the mid 80's to low 90's across Southern Illinois, to the upper 70's to mid 80's across Northern and Central Illinois. Heat index values in the mid 80's to mid 90's across Southern Illinois. Low temperatures in the low 60's to low 70's across the state.

Recap Summary...
Tuesday, July 14th Recap...
High temperatures topped out in the upper 80's to low 90's across Southern Illinois, with mid 80's Northern and Central Illinois. Heat index values were in the upper 80's to mid 90's across Southern Illinois, and mid to upper 80's across Northern and Central Illinois. Low temperatures in the low 60's to upper 60's were common across the state.

Wednesday, July 15th Recap...
High temperatures topped out in the upper 80's to mid 90's across Southern Illinois, with upper 70's to upper 80's Northern and Central Illinois. Heat index values in the low 90's to low 100's occurred across Southern Illinois, and upper 70's to low 90's across Northern and Central Illinois. Low temperatures in the low 60's to low 70's were common across the state. Periods of showers and t'storms occurred across the state, which kept areas such as Northwest and Western Illinois cooler.

Thursday, July 16th Recap...
High temperatures topped out in the upper 80's to mid 90's across Southern Illinois, with mid 70's to upper 80's Northern and Central Illinois. Heat index values in the low 90's to low 100's occurred across Southern Illinois, and mid 70's to low 90's across Northern and Central Illinois. Low temperatures in the low 60's to low 70's were common across the state. Periods of showers and t'storms occurred across the state, which kept areas such as Northwest and Western Illinois cooler.

Friday, July 17th Recap...
The ridge started to flex into the region a bit more on Friday, leading to more widespread hotter and humid conditions across the state. High temperatures topped out in the upper 80's to mid 90's across the state. Heat index values ranged from the upper 80's to mid 90's across Northern Illinois, to the low 90's to low 100's across Central and Southern Illinois. Low temperatures in the low 60's to mid 70's were common across the state.

Saturday, July 18th Recap...
The core of the ridge flexed into the region on Saturday, bringing the most widespread hot and humid conditions of this period. High temperatures topped out in the upper 80's to mid 90's across the state. Heat index values ranged from the mid 90's to upper 100's across the state. Low temperatures in the low 60's to mid 70's were common across the state. Isolated showers and t'storms moved across Northern Illinois, though this activity did not temper conditions much.

Sunday, July 19th Recap...
A "cold" front pushed southward across the state on Sunday. Along with the front came scattered showers and t'storms, which pushed across Northern and Central Illinois Sunday morning into afternoon and Central and Southern Illinois Sunday afternoon into night. High temperatures topped out in the low to upper 90's across Southern Illinois, and the mid to upper 80's across Northern and Central Illinois. Heat index values ranged from the mid 90's to upper 100's across Southern Illinois, to the mid 80's to low 90's across Northern and Central Illinois. Low temperatures in the mid 60's to upper 70's were common across the state.

Monday, July 20th Recap...
High temperatures topped out in the mid 80's to low 90's across Southern Illinois, to the mid to upper 80's across Northern and Central Illinois. Heat index values in the upper 80's to mid 90's across Southern Illinois. Low temperatures in the low 60's to low 70's across the state. Periods of scattered showers and t'storms pushed across Central and Southern Illinois, tempering the heat for some areas.

Tuesday, July 21st Recap...
High temperatures topped out the upper 80's to mid 90's across Southern Illinois, and the low to upper 80's across Northern and Central Illinois. Heat index values were in the upper 80's to upper 90's across Southern Illinois. Low temperatures in the low 60's to low 70's were common across the state. Periods of scattered showers and t'storms pushed across the state at times as a "cold" front approached, which tempered the heat for some areas.

​JP

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