An oncoming thing or situation is approaching quickly, often unexpectedly.
When we use the word "oncoming", we usually talk about something that's moving towards us, like traffic coming around a bend, a storm heading our way, or a problem that's getting closer. For example, if you're driving and see headlights in your rearview mirror, they're oncoming traffic - cars are approaching from behind you. We might also use "oncoming" to describe a situation where something is developing quickly, like an oncoming financial crisis or an oncoming wave of new customers for a business.
moving toward one
the beginning or early stages
Example: the onset of pneumonia
