Portents or harbingers were unexplained, rare incidents that signalled the coming of possible apocalypses.
Prior to the rise of The Master and the opening of the Hellmouth, several events happened in a radius of three miles around Sunnydale. These events included:
- A cat gave birth to a litter of snakes and then was devoured by them.
- Whisper Lake suddenly began to boil, killing two members of a family swimming in the it.
- At Mercy Hospital, a boy was born with his eyes facing inwards.
- An earthquake, possibly 5.1 Richter, though earthquakes were common events in California and the entire American coast of the Pacific Ocean.
- Stones rained from the sky.
- The water supply of Sunnydale turned into blood for a time.
- When the Sisterhood of Jhe attempted to open the Hellmouth, Angel claimed to have seen portents which convinced him that the apocalypse was due to happen. Though, he did not specify what they were.
- "This thing caught you by surprise, too. You had no idea it was coming."
- ―Angel to Lilah Morgan[src]
In late 2002, several events heralded the coming of The Beast, a powerful demon believed to be a harbinger of apocalypse, though he turned out to be nothing more than the enforcer for another being. According to information revealed to Lilah Morgan, the night of the Beast's ascension, Wolfram & Hart registered a 300% increase of unexplained events in the Los Angeles area. All these disturbanced formed a square shape. These portents included:
- Hundreds of rats emerged from pipes and drains, possibly driven away from their sewer dwellings
- Swarms of insects.
- A cat tried to devour its owner.
- Sparrows committed suicide en-masse.
- An earthquake struck Los Angeles.