The mid-week could be a little bumpy so you better buckle up.
The week starts with temperatures in July-like form - highs in the middle/upper 80°s. By the weekend temperatures will be down in the 30°s. A near 50° swing over the course of the week and the bulk of the drop will happen over a 72-hour period. If you enjoy the summer temperatures, you are on the clock!
Colder air has already infiltrated the northern United States. As of 6pm Sunday evening, temperatures are only in the 30°s and 40°s from North Dakota to Colorado. The snow level has dropped to around 9,600 feet in Colorado.
The country will be divided to start the week. Temperatures in the western half of the country will be below normal. The eastern half will be the opposite. Temperatures will remain well above normal.
The colder air will begin to march to the east behind a cold front that will pass through the Midwest mid-week. Ahead of the front, temperatures will continue to climb in to the 80°s in central Indiana. Behind the front, temperatures will be in the 40°s, 50°s and 60°s.
As of this writing, computer models suggest the transitional time will be Wednesday afternoon through early Thursday morning. Temperatures should climb in to the lower 80°s Wednesday prior to the front passing. Showers and thunderstorms will move in from the west that afternoon/evening as the cold front arrives. The front should be through the area by late Wednesday night.
There remains some question as to how far behind the cold front the cold air will be. Sometimes the much cooler air can lag a few hours behind the front. That being said, expect Thursday's high temperature to occur around 1am.
Many areas of central Indiana are beyond their normal first frost. Using the map below you can see most areas outside of larger cities typically get their first frost September 30 through October 6.
The normal first frost in Indianapolis occurs October 11. Here are the normal first date, latest date, and earliest date of patchy frost for various cities around central Indiana.
High temperatures Friday aim to be near normal levels in middle November. Looking beyond the 7-day, some data suggests we could have one or two more warm-ups before October is over, but the summer heat appears to be over after Wednesday.