The heat will return next week.

Enjoy Friday and Saturday. The heat returns on Sunday with a high of 90 degrees. The heat will hang on though much of next week. Here's what the NWS says:

Long Term...(Friday night through Thursday)
Issued at 141 PM EDT Thu Aug 31 2023

Hot temperatures are the main focus in the long term portion of the
forecast. It still appears heat indices will stay below critical
levels, and likely below 100F, but there are some uncertainties. See
analysis below for details. A low probability of rain emerges by
around the middle of next week, but dry weather will prevail until
then.

Since the pattern is somewhat different with the upcoming period of
heat compared to the previous period of heat, there are model
performance considerations. Questions include: 1. magnitude of
moisture return and 2. model bias with regards to temperatures
(which was an issue for the last period of heat). The previous event
saw anomalous moisture which was deep enough not to mix out and this
impacted temperatures (cooler than modeled). It also contributed to
high heat indices and heat related impacts.

On the synoptic scale, forecast confidence is quite high with
anomalous 500-mb heights. Multi-model ensemble run-to-run
comparisons may show a slightly more amplified/anomalous ridge and
slightly further east position into early next week, but generally
negligible changes sensible weather. It is these minor details with
potential model biases and moisture magnitude to could result in
minor shifts in our forecast over the next few days. We do not see a
path where we would substantially exceed 100F for heat indices,
however, given the synoptic-scale stability in medium range
guidance. So, heat-related illness should be fairly minimal during
this upcoming anomalously warm period.

There is a low probability of some precipitation Tuesday night into
Wednesday. It does appear that on the periphery of eastern surface
high, at least modified moisture return will occur early-mid week.
There is an upper low with low latitude subtropical origins that
will eject northeastward ahead a shortwave trough and potentially
enhance mid-high level moisture. This, in addition to modified low-
level moisture, should push precipitable water values above
climatology. As the aforementioned shortwave trough`s associated
front moves through sometime between Tuesday night and Wednesday
night (there is spread in the medium-range models), interacting with
moisture, this should bring at least sparse coverage of convection
across Indiana.

Looking beyond the 7-day period, there is above confidence in
continued above normal temperatures given the signal in the medium-
range ensemble suite. This should be a mostly dry pattern as well.