Signs can be ambiguous, or they can be very certain. There are the ‘signs’ of the sacraments fall into the latter category, given to us to ensure we are given grace, in its various forms, not least the Real Presence of Christ in the Holy Eucharist. Then there are the certain signs of the approved sacramentals, by which, if we use them rightly, are definitely dipositive to grace.
Then there are the less certain various ‘signs’ in our world, the great and the small, that may, or may not, signify God’s providence, His presence and action, not least the ‘signs in the sky’. True enough, our Lord warned that it is a wicked generation that seeks a sign. But He also said that sometimes there are signs that are given to us, to wake us from our spiritual sloth and slumber, saying that we should keep our wits about us, and our eyes, sometimes, above us:
And there will be signs in sun and moon and stars, and upon the earth distress of nations in perplexity at the roaring of the sea and the waves, men fainting with fear and with foreboding of what is coming on the world; for the powers of the heavens will be shaken.