What were some of the signs that Mt.Vesuvis from Pompeii was going to erupt?

Question

What were some of the signs that Mt.Vesuvis from Pompeii was going to erupt?

Answer 1

There are no reliable witnesses of what happened in 79 AD aside the one released in a letter written by Gaius Plinius Caecilius Secundus better known as "Pliny the Younger".

Therefore unless you prefer to read fancy descriptions of what happened before that eruption (and based on which are generally the premonitory signals of nowadays eruptions) I can translate for you from Latin what has been described by

'Pliny the Younger':

«Nonum kal. septembres hora fere septima mater mea indicat ei apparere nubem inusitata et magnitudine et specie.».

«The ninth day before September kalends (August 24th), around the seventh hour (from 12 till 1 p.m.), my mother showed to him an unusual cloud, uncommon both for shape and bigness.»

Answer 2

Zeus was pissed off, Nero was pissed up, Pompeii was pissed on.