Todays word: unpredictable

unpredictable
adjective
tending to change suddenly and without reason and therefore not able to be predicted (= judged in advance) or depended on:
The weather there can be a bit unpredictable - one minute it's blue skies and the next minute it's pouring down.
The hours in this job are very unpredictable - you sometimes have to work late at very short notice.