Mark V says:

I’m going to add a tiny caveat. There are extremely rare times when a volcano will appear out of nowhere. Extremely rare.

On February 20, 1943, a fissure appeared completely unexpectedly in a cornfield outside of the small town of Paricutin, Mexico. The surface bumped up by 150 feet, and everyone fled. Only a day later, it had grown by an additional 120 feet, and would continue to grow by 30 feet per day until it reached its final height of 1,391.08 feet. Nobody saw it coming.

However, this volcano wasn’t deadly. It grew quickly, but it wasn’t a massive, uncontrolled explosion, and people were able to evacuate without incident. In fact, since 1943, there have only been three deaths recorded.

But yes, otherwise, we pretty much know where volcanoes will erupt, when they will erupt, and how they will erupt (effusive or explosive). People can be evacuated accordingly.