Temperatures Sunday afternoon should be similar to what central Indiana experienced Saturday afternoon. Expect high temperatures in the low 90°s.
One difference from Saturday, winds will be a bit more brisk at times, gusting to near 20 mph out of the south.
The southerly winds will help keep low-level moisture in place. Dew point temperatures - the measure of the moisture in the air - will remain in the low to mid 70°s throughout the day. This will take heat indices in to the upper 90°s. A few locations in northern Indiana and near the Indiana/Illinois state line may cross in to the lower 100°s.
Peak heat indices will remain in the upper 90°s to near 100° for the next several days. There will be a "slight" drop in the heat index Monday, but it will still feel like it is in the middle 90°s.
An approaching cold front will try to send a few showers and thunderstorms to central Indiana Sunday night. As is typically the case, as we get closer to the "event" computer models start to back off on the coverage of rainfall and how much moisture will fall. On average, computer models suggest around 0.15" of rain could fall through Monday morning.
The best chance for rain will come late Sunday night through early Monday morning.
There will be another chance for afternoon showers and thunderstorms Monday and Tuesday. However, they will be hit and miss and most locations will remain dry. Computer models only suggest there is about a 20% probability of rain falling so don't stop watering your lawn/plants due to the prospects of rain.
Temperatures spike for the 4th of July as a strengthening area of high pressure in the upper-levels of the atmosphere builds in overhead. We also call the upper-level high a "hot dome". The hot dome will be overhead for a couple days. This should take temperatures in to the lower/middle 90°s and send the heat index back to the upper 90°s to lower 100°s.