I'm not sure about there, but I've noticed that the biggest factor for its appearance out here is a sudden calm as well. The slime mold tends to dry out very rapidly out here, and it's usually ready to sporulate when we get our sudden sporadic rainstorms. Combine that with the steady south wind we get between May and November, and those quick rainstorms guarantee a maximal spread of spores before ants and sowbugs can eat them.