Fall continues it's march south. The morning temperatures this past week were more like July than late September, but this week will see a big change. The forecast is calling for daytime highs in the upper 50's and lows in the low 40's. I think we'll see some mid 30's in the morning this upcoming week though. There might even be some patchy frost.
Speaking of frost, the typical date of the first low temperature of 36 or lower for this area is October 3. At 36 degrees, patchy light frost can occur. The typical date of the first low temperature of 32 or lower is October 14. At this temperature, widespread frost will occur with a possibility of a hard freeze in some areas. The typical date of the first low temperature of 28 or lower is October 27. At this temperature, a widespread hard freeze occurs. This will signal the end of the growing season. Data from the Indianapolis NWS. http://www.crh.noaa.gov/ind/?n=frostfreezedate