The Yellowstone River is one of the legendary trout streams of the west and over the years it has produced some very nice Brown Trout during the fall. As by way of definition the time period in question, it runs from approximately mid-September to Late October. The best fishing times may vary slightly from year to year based on general over-all weather cycles. In 2018 the fall was more normal, or what we in Montana consider normal. The weather began to cool and the water temperatures began to drop, The Brown Trout leave their normal holding lies and begin to gather in the pool to begin their annual movement to their spawning grounds. In 2018 this cooler water temperatures appeared in mid-September.