Spring Showers

Only a few lonely patches of snow remain on the hill behind our old farmhouse this morning after days of warm breezes and yesterday's fitful rain showers. I heard the heavy rain on the skylights last evening but I missed the promised thundershowers. I mention this here because I remember someone telling me that there was a correlation between the first thunderstorm of spring and the first frost date in the fall. Do any of you know of that old farmer's tale?