Southern Indiana is at its best in late spring and autumn. May and June bring warm, sunny days and the dogwoods and redbuds flowering through the karst woodland. October is reliably spectacular, with the hardwood forests turning red, orange, and yellow.
Summers are humid and can be uncomfortable, with afternoon thunderstorms and temperatures regularly into the 30s Celsius. The caves stay cool year-round, which makes Bluespring Caverns and Spring Mill an appealing summer escape. Winters are cold and grey but rarely severely snowy; the Limestone Heritage Festival in late June is the local headline event if you want to time a visit around something specific.