The Stone Toad

You come across a small pond, about 50 feet across. On a very small island, is a enormous stone statue of a toad. The statue is uncannily life-like, but otherwise does not seem unusual. Except for one small detail. Every mid-day, the toad animate and lets loose a loud croak. Anyone who hears it must save against spell. Those who fail suffer a slight headache, but acquire the ability to predict the weather for the next 24 hours with perfect accuracy.