The “Three Days of Darkness” is a private revelation of several Catholic saints and mystics. It is said to be three days where there will be no light and hell will be loosed upon the world. Whether this lack of light is to be taken literally or figuratively is debated. Threats of the action of Divine Justice are often given to change behavior and can be avoided if the appropriate change takes place. It is debated whether the “Three Days of Darkness” were averted due to appropriate repentance and penance or whether it is still to come.
Either way, private revelations are not binding on the faithful. Catholics are free to debate the whether the Three Days of Darkness is still to come or to believe it is completely symbolic.