Some years the Leonids are amazing, other years there are very few - are these predictable at all, following trends or at least reasonably accurate predictions?
Most meteor showers are associated with comets, they are either remnants of a dead comet or simply orbiting in the same orbit as the associated comet, so their strength can be predicted by how closely earth intersects with the orbit, where the observer is on Earth, and at what point the biggest "clump" of cometary fragments are in the orbit.
To use your Leonid example, it is known that leonid "storms" sometimes recur in cycles of 33 to 34 years.
That said, most showers are notoriously unpredictable. We never know for certain if viewing conditions will be right, if the angle of intersection with the orbit will produce many meteor trails, whether our predictions of the density of the number of meteors is correct, and so on.
I have found this page which has meteor show predictions and more discussion on how meteor shower strength is predicted.