Update 5PM CDT...
The Excessive Heat Warning has been extended into Sunday evening for most of northeast Illinois and northwest Indiana including the city of Chicago
The Excessive Heat Warning is now in effect for essentially all of northeast Illinois and northwest Indiana including the city of Chicago into Sunday evening. Daytime heat indices will run 100 to 110-degrees, even higher in a few locations, while nighttime temperatures will drop no lower than the mid 70s (outlying areas) to lower 80s (Chicago).
Lowering clouds and thunderstorms are expected to move into westernmost portions of the Chicago area Sunday afternoon, moving east and spreading over the remainder of the Chicago area by later in the evening. Thus some relief from the heat could occur by Sunday afternoon in Winnebago, Boone, DeKalb, Ogle and Lee Counties, but even in those counties the heat index may well exceed 100-degrees, before cooling showers/thunderstorms arrive.
Sunday will mark the third consecutive day with dangerous heat indices well above 100-degrees and little or no relief at night - temperatures dropping no lower than the mid 70s to lower 80s. This is an extremely rare event for our area, and the cumulative effects of oppressive heat and humidity will take a toll on individuals with respiratory or heart problems, elderly and children, unless relief is provided by air-conditioning or other cooling methods.
This can be a life-threatening situation, so check-in on those deemed in need and provide aid, if possible. Some cooling should occur area-wide Sunday night.
An Excessive Heat Warning continues in effect for the entire Chicago area, including Chicago as well as northern Illinois into northwest Indiana into the overnight hours Saturday night (reference the purple-shaded area on the headlined map) – The Excessive Heat Warning is extended through Sunday for the city of Chicago.
Dangerous heat indices should again range from 105 to 115-degrees Saturday with even higher values possible, as temperatures reach well into 90s this afternoon and overnight low temperatures fail to provide much if any relief dropping only into the mid 70s and lower 80s – highest overnight readings will occur in the city of Chicago where the heat index may not drop much below 90-degrees for the second straight night.
There may be scattered clouds this afternoon, but abundant sunshine will effectively add another 5 to 15-degrees to the heat indices, making conditions extremely dangerous. Very high humidity will be sustained and even increased due to still wet soils from recent rains, evapotranspiration from a growing corn crop and a replenishing of already high dew-point air flowing into our area from the Plains and Mississippi Valley. These factors along with an increase in high and mid-level clouds will all contribute to near-record high overnight temperatures again tonight, again providing no relief from the heat, especially in the Chicago “heat island."
The increased cloudiness and possibility of showers/thunderstorms Sunday, as a cool front makes its way east across our area is expected to restrict high temperatures to the lower 90s with heat indices more in the 100 to 106-degree range. The Excessive Heat Warning will continue for Chicago itself, where the cumulative-effects of the oppressive heat will last longer and be greater. If it is determined that clouds/thunderstorms may be delayed, the Excessive Heat Warning could be extended again over the entire northeast Illinois/northwest Indiana area Sunday.
For at least another 24 to 36-hours, make sure you check-on and assist those most susceptible to the heat and humidity – people with respiratory or heart problems, children and elderly, especially those with no access to air-conditioning. If you must be outside during the late-morning/afternoon, stay out of the sun as much as possible, seek shade and drink plenty of water.
- Drink plenty of fluids
- Never leave a child or pet in a hot car
- Avoid drinks with caffeine or alcohol
- Try to stay in the shade or indoors as much as possible
- Check on elderly neighbors and those with functional needs
- Take pets indoors and make sure they have plenty of water