You've probably heard by now that big-time heat is on the way for Michiana. That is still the case. Friday, Saturday and even Sunday are shaping up to be three of the hottest days South Bend has seen in the last six years when factoring in both daily high temperatures and low temperatures. Each afternoon, we will see the mercury climb into the 88-95° range. At night, we will only drop into the lower and middle 70s.
It's not only the actual air temperatures that you must consider, though. The humidity needs to be factored in to get what is called the heat index. That is what it will feel like to your skin as you step outside. Unfortunately, the humidity will be sky high Friday thru Sunday. As a result, the heat index will be in the 97-108° range during the daytime hours this weekend. But just how high are we expecting the humidity to be? Put simply, we will be in unprecedented territory.
Dew point temperatures are expected to soar well into the 70s and perhaps approach the 80-degree mark. That just doesn't happen in northern Indiana or southern Michigan. Dew point temperatures above 70° are representative of a very muggy, oppressive air mass. Once you approach 80°, it feels miserable outside. 80-degree dew points are even high for cities like Key West, Miami, New Orleans, Houston, and Myrtle Beach. The average dew point during the summertime in those beach cities is in the lower and middle 70s. Again, we just don't see dew points that high.
For perspective, South Bend has only recorded a dew point temperatures in the 80s on six different dates since 1980. The most recent occurrence was an 81-degree reading back in July of 2012. That's not all, though. Since 1980, South Bend has only spent 12 hours with a dew point temperature at or above 80°. That's 12 out of 337,360 hours since the beginning of 1980! Once again, it just doesn't happen this far north. It's incredibly rare to see an air mass capable of sending our dew points into the lower 80s at this latitude. It's even uncommon to see dew points eclipse 75°. As of now, 75° appears to be a given. Will we hit that unprecedented 80-degree mark? It's certainly not impossible. Regardless, be ready for one of the most humid 3-day stretches in South Bend history!