While our daytime highs across the state have been in the upper 70s, our nighttime lows have been in the 40s. This is a great time to start thinking about the timing of the first frost and freeze events of the season when the 7-day average 4-inch soil temperature falls before 50°F, and the viability of your home’s furnace. The Midwestern Regional Climate Center (MRCC) can help provide historical climatologies of the first two of those three. They keep positive thoughts for the third item!
The typical date of the first freeze event in your area can be explored using the MRCC’s Freeze Date Tool (Figure 1). This tool uses county data to illustrate the earliest, average, latest, and other climatological timing of the first fall and last spring dates of when the temperature fell below or above temperature thresholds, respectively. Users can choose temperature values ranging from 20°F to 40°F and then mouse over their county of interest to see historically when those temperature thresholds were crossed. Clicking on a county will take the user to a new screen that will show the historical dates from 1950-2023 for all temperature threshold options. Since the date of the last spring freeze and first fall freeze can often be used to define the length of the growing season, users can also select the “Growing Season Length” tab of the tool to see how the growing season length has varied for their location over the years using user-defined temperature thresholds.
Figure 1. Screenshot of MRCC’s Freeze Date Tool main page.
Another online tool users may find interesting is the MRCC’s Soil Temperature Climatology Tool. (Figure 2). Using gridded data from 1991-2020, users can identify dates when the 7-day average 4-inch soil temperature either cools below (e.g., late fall) or warms above (e.g., spring) particular temperature thresholds. Knowing the climatology of these dates can provide decision support for agriculture activities such as planting and nutrient applications as well as other soil temperature-dependent events. Users can also leverage this tool to explore the typical 4-inch soil temperature values on a particular date. Temperature thresholds that users can select range from 30°F to 60°F.
Figure 2. Screenshot of MRCC’s 4-inch Soil Temperature Climatology Tool main page.
Aside from the few rainfall events that Indiana experienced several weeks ago, the state remains in a dry pattern. This has led to the majority of Indiana being classified as at least Abnormally Dry (D0) to being in Moderate Drought (D1), according to the U.S. Drought Monitor (Figure 3). Aside from a possible chance of rain in northern Indiana near the end of this upcoming weekend, both the 7-day precipitation forecast and the 6-to-14-day climate outlooks are favoring below-normal precipitation patterns to continue.
Figure 3. U.S. Drought Monitor conditions through October 15, 2024.