At Wonders and Marvels, a whole list of guide- and guidebook “truths” that may not be so.
It starts with this:
Myth #1 – Vesuvius Did Not Erupt on 24 August AD 79. Everybody confidently quotes this as the date of the eruption, but everybody is probably wrong! At the turn of the 20th century, everybody claimed the eruption occurred in November. But Wallace-Hadrill thinks late September or early October is a likelier date. His clue is a lot of ripe pomegranates found near a buried villa at a place called Oplontis between Pompeii and Herculaneum. (This villa is known as the Villa Poppea or Villa Poppaea because it was owned by Nero’s wife Poppaea.) In Italy, pomegranates ripen in late September/early October. The problem is not with Pliny the Younger, whose famous letters tell us the date of the disaster, but with the monks who interpreted his dates as they copied his manuscripts.