Day of Fury

The Days of Fury are global disturbances that affect the planet Mobius periodically in history. They are described in the Echidna Tomes as "Natures way of adjusting to environmental changes it undergoes over a certain duration" according to Athair.

First Day of Fury
The first Day of Fury occurred approximately 12,000 years ago, several decades after the Xorda race attacked the planet via the Gene Bombs. The bombs, which were supposed to preserve the planet's environment as it was at the time of their use, instead triggered massive volcanic reactions on a global scale, which hurled billions of tons of dirt and ash into the planet's atmosphere, preventing most sunlight from reaching the planet for over a thousand years. (StH: #148)

Second Day of Fury

 * See also: Coming of the Chaos Emeralds

The Second Day of Fury occurred roughly 10,000 years ago, when the remaining energies of the Gene Bombs reacted with beryl deposits beneath the planet's surface, forming the Chaos Emeralds. Once formed, a cataclysmic reaction happened, sending the Chaos Emeralds into the sky, only for them to rain down upon the planet once again. The resulted in the extinction of the Mobosaurs, a dinosaur-like race which was the newest dominant species on Mobius. (TMS: #3)

Recent Days of Fury
Another Day of Fury occurred roughly 1,200 years ago according to the Echidna Tomes. (KtE: #10)

The most recent Day of Fury occurred in 3236, causing severe weather changes all of Mobius. Sonic the Hedgehog and Miles "Tails" Prower were forced to land their plane Winged Victory because the stormy weather was so bad. Even parts of Angel Island, such as Sandopolis and Echidnaopolis, were affected by the Day of Fury. The weather patterns there adjusted from blizzard snow storms to turrential rain fall. (KtE: #10)


 * It is likely a rather massive Day of Fury occurred 3237 years ago (when the year was "0" for the Mobian calandar) though this is not known for sure.