What does a normal April look like across Indiana? If you're looking ahead thinking about what the early planting season could be like, one of your best guides are historical averages. The numbers in the table are based on 30-year averages from 1981 through 2010.
Here is some information that will help you better understand the table. The table is provided by Ken Scheeringa and the staff at the office of the Indiana State Climatologist.
First, note that the temperatures are averages of the daily high in degrees F, and the nightly low. As you move farther south in the state, the maximums go higher and the nighttime lows also go higher. For example, there's nearly a 5-degree spread in average daily temperature in April from southwest to northwest Indiana.
It help explains why lawn mower sales and early season repairs run two to three weeks ahead in the southern part of the state compared to northern counties in Indiana.
The surprising trend may be in rainfall. Based on this historical data, there is more than an inch difference in precipitation received in the April period between northwest and south-central Indiana. Overall rainfall amounts have been historically higher in southern Indiana for April than in northern Indiana.
The table paints a fairly accurate picture. If this year is anywhere near normal, spring will appear to arrive two to three weeks earlier in southern Indiana compared to extreme northern Indiana. It's especially true between southwestern Counties and northeastern Counties, for example.
The net result is that field work should be able to start earlier in the south due to warmer temperatures. However, it is more likely to get drawn out by wetter weather in southern counties.