Average First Frost/Freeze 10/2 INDIANAPOLIS (WISH) — A cold front passage made for a cooler Wednesday morning in central Indiana. Lows bottomed out in the mid-40s, which will have residents thinking: When do we normally get our first frost and first freeze? Frost Formation Usually, when you have clear skies and an air temperature of 36 or lower, frost is possible. The main reason for this is the air above the surface takes longer to cool down than the surface. An air temperature of 36 a few feet off the ground can translate to freezing temperatures on the surface. Normal First Frost Dates According to the 1991-2020 climate averages, Indianapolis has an average first frost of Oct. 17. A frost is considered any day with a low temperature of 36 degrees or below. Lafayette has already passed their average date which is Sept. 30. Normal First Freeze Dates Mid-late October is the general timeframe for our average first freeze. For Indianapolis, that average first freeze date has been Oct. 26 from 1991 to 2020. All these averages are not an exact forecast and just climatology for our area. To find the latest day-to-day forecast visit our weather blog here.