No record high temperatures were broken over the weekend with highs staying in the lower 90s for the most part. Some locations reached the mid-90s on Sunday and again Monday, but South Bend stayed just below record territory. When factoring in the near-record high dew points, heat index values eclipsed 100° for several hours both Sunday and Monday afternoon. And, this heatwave has doubled our total number of days in the 90s so far in 2018. The first three days at or above 90° came back in late May with the year's first heatwave. Now, South Bend has seen 90° a total of six times this year despite the calendar still saying "spring." South Bend hasn't seen this many 90-degree days this early in the year in quite some time. Dating back to 2015, no one year saw more than three days in the 90s by June 18th!
Last year, South Bend only saw 90° seven times! We are knocking on that doorstep without even officially beginning summer this year! Looking ahead, it does not appear as though we will threaten the 90-degree mark over the next 10 days. That's not to say the humidity won't be high, but intense heat like Michiana is currently experiencing is unlikely through the remainder of June.
Let's rewind back to the record temperature discussion. While South Bend didn't break any record high temperatures during this heatwave, the city did break the record for the warmest low temperature for June 18th (Monday). Assuming temperatures don't drop below 77° before midnight Tuesday, we will officially have a new record for the warmest low temperature ever on June 18th. The next-warmest low ever recorded on the 18th is 73°. In other words, we essentially shattered the previous record. Even more, we tied the second-warmest low temperature ever in the month of June! The warmest low for the month is 78°, and there was one other instance in which the low temperature was 77°. Low temperatures rarely stay above 75° in northern Indiana and southern Michigan. It takes many meteorological factors coming together perfectly to string together a day or two with overnight lows above 75°.