Groundhog lore
If Candlemas Day be fair and bright,
Winter will have another flight,
But if it be dark with clouds and rain,
Winter is gone and will not come again.
-- old English rhyme
February 2 is known to us today as Groundhog Day, but that is a fairly recent development. For centuries, February 2 was celebrated as Candlemas Day (also known as Saint Bridgid's Day), a traditional Christian holiday. However, it's no coincidence that Candlemas just happens to fall on the very same day as Imbolc, an even more ancient pagan holiday which marks the calendar midpoint between the winter solstice and the spring equinox.
As the poem above suggests, folklore ascribed predictive power to the weather on this day. In the colder regions of medieval Europe, this eventually developed into observing the habits of hibernating animals such as badgers. If a badger emerged from hibernation on this day, and the weather was sunny enough for it to see its shadow (and flee "in fear" back to its burrow), then "six more weeks of winter" would ensue. But if the day was cloudy, the badger would not be spooked by its own shadow, and stay out for a while. This was said to be a harbinger of an early spring.
The Europeans who migrated to America brought this tradition with them, especially the German farmers (aka "Pennsylvania Dutch") who settled in Pennsylvania for its religious freedom and world-class farmland. Although there were no badgers to speak of in Pennsylvania, there were "good and plenty" of groundhogs. These are the humble origins of what we now call Groundhog Day.
Of course, all of this may seem to be mere superstition; as a famous comic once said, "I'm not superstitious... but I am a little stitious." Nevertheless, Octoraro Orphie's legacy of over 100 years of perfect prognostication is all the proof that a true believer needs.