The phrase "most premonitory" refers to something that is particularly predictive or forewarning. When considering antonyms for this phrase, we need to think about words that suggest the opposite - that is, a lack of prediction or warning. Some possible antonyms could include "unanticipated," "unexpected," "surprising," "abrupt," or "sudden." Each of these words implies a lack of foresight or advance notice, which stands in direct contrast to the idea of something being premonitory. By exploring these antonyms, we can gain a better understanding of the qualities that make something premonitory and the ways in which such qualities can be reversed.