I think it's always been the case that vernal pools can vary greatly from one year to the next, so I wouldn't read much of anything into short term observations. Using temporary pools to breed in has always been a risk.
An increase in global temps, which will speed up the drying of vernal pools, is supposed to come with increased precipitation, which helps keep vernal pools flush with water. Which wins seems to depend on the specific climate change models used for predictions as well as the location and makeup of the pond. There's plenty of reading material on vernal pools and climate change, I've only looked at a teeny tiny bit of it, but it's out there if you're interested in delving deeper
