What would be a normal crawl space temperature in the summer? I live in southern indiana. My crawl space has a vapor barrier over the bare ground and 5 automatic vents. I'm trying to diagnose if I have significant supply ductwork leakage in this area. I would guess that if I do, my crawl space temp will be below normal when the a/c is running. I measure my crawl space temp at 62 degrees with 80% RH. I know the caves in my area run about 52 degrees year round.