Late June-Early July Heat Wave

(6:00PM - 7/3/20) As was mentioned in a post from earlier this week, a warm/hot and deep summer weather pattern has settled into the region. This pattern is expected to continue through early to mid July, and will feature the first heat wave of the season for the state.

Things have kicked off this week, with widespread warm to hot temperatures across the state. High temperatures across the state this week have generally ranged from the mid 80's to mid 90's...the exception being areas that had been impacted with t'storm activity. The combination of high temperatures and high dew points lead to high humidity and heat index values for a few of the days. Heat index values of 100-106 occurred across portions of Northern and Central Illinois for a few days, early to middle of this ending week.

Looking forward...Increasingly hot temperatures are expected this weekend across the state, with high temperatures in the upper 80's to mid 90's expected for most areas. ​An isolated t'storm will be possible anywhere across the state each day, which could temper heat for a few areas at times. Dew points in the low 60's to low 70's, combined with the high temperatures, will lead to heat index values in the upper 80's to upper 90's. Low temperatures across the state will range from the low 60's to low 70's on a nightly basis.

For the upcoming week, the main heat wave will occur, with high temperatures across the state likely to range from the low to upper 90's on a daily basis. However, some t'storm activity may be possible for some areas from time to time, which could temper the heat in a few areas at times. Additionally, dew points will be on the rise early in the week, and then remain high mid through late week. The combination of high temperatures and high dew points will lead to high humidity and heat index values. Early week heat index values in the low 90's to low 100's are likely across the state, increasing to the mid 90's to upper 100's for mid to late week. Low temperatures across the state will be in the mid 60's to mid 70's for more areas on a nightly basis, and likely warmer in the mid 70's to around 80 for more urban areas, such as Chicago.

There are signs that the heat could persist beyond this upcoming week, through next weekend (11/12th). However, confidence at that range greatly decreases, thus will not go too far into that potential for now.

Saturday, July 4th Forecast...
High temperatures ranging from the low 80's to low 90's across the state, with cooler temps expected in Northeast Illinois near Lake Michigan. Heat index values in the upper 80's to upper 90's across the state. Low temperatures in the low 60's to low 70's across the state.

Sunday, July 5th Forecast...
High temperatures ranging from the low 80's to mid 90's across the state, with cooler temps expected in Northeast Illinois near Lake Michigan. Heat index values in the upper 80's to upper 90's across the state. Low temperatures in the low 60's to low 70's across the state.

With all of that said, for now an overall low heat wave impact is expected. However, as conditions for this upcoming week become more clear, an upgrade to moderate impact is likely. 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.

JP

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