onset
ON-setnounMeaning the beginning of something, usually something unpleasant
Memory hook ON-SET: the storm SETS ON. The sky darkens and the first raindrops fall: the storm is setting on. At its onset, the picnickers grab their baskets and run.
At the onset of the storm, the picnickers grabbed their baskets and ran.
In context With the onset of winter, the birds that had crowded the feeder all summer flew south, and the garden grew silent.
Similar outbreak, arrival, first signs, coming
Opposite end, close