Wet, cold, and slimy.
Great adjectives for our ribbiting amphibian friends but if they also describe your compost pile, you’ve got a problem.
Your pile is likely compacted from too much fresh grass or other matting material. This means it has too much water and not enough air. When your pile doesn’t get enough air the aerobic bacteria (air-loving, good bacteria) cannot survive and that makes way for anaerobic bacteria (the bad smelling, slow composting arch nemesis of aerobic).
While you do want some water in your pile (think wrung out sponge), too much can create oxygen starved pockets of slimy anaerobic compost. Yuck.
The fix is easy. Get in there and fluff up your pile by turning it with a shovel, pitchfork, or compost turner. Add some shredded leaves, shredded paper, sawdust or other fibrous material to reduce the matting effect. With the added air, your friendly aerobic bacteria should start heating your compost and we can happily leave wet and slimy where they belong, with the frogs.