Activities The Great Outdoors Catching Huge Montana Brown Trout in the Fall Share PINTEREST Email Print Karen Desjardin / Getty Images The Great Outdoors Fishing Freshwater Fishing Saltwater Fishing Gear Fish Species Hiking Climbing Skiing Snowboarding Surfing Paddling Sailing Scuba Diving & Snorkeling Learn More By Brian Milne Updated September 03, 2018 Montana is home to some really large brown trout. These big fish are often notoriously hard to catch and many anglers that fish waters in the Big Sky state never land a brown over 22". The monster browns over 2 feet long (sometimes even over 30") are both smart and elusive. To land these massive fish you need stack as many cards in your favor as possible. One of the best strategies is to simply fish in the fall. Brown trout are late fall spawners and the time leading up the the spawn is a great time to catch big browns with their guard down when they are aggressive and less warty. Here are six tips for catching the trout of a lifetime in the fall, courtesy Brian McGeehan, owner and outfitter of Montana Angler Fly Fishing. McGeehan has been a professional guide for 18 years and enjoys targeting big browns in the fall. Fish Late into the Fall Many visiting anglers think of fall fishing in Montana as September and early October while the weather is typically predictably pleasant. Although early fall is a wonderful time to fish the Big Sky, the browns don't start moving in earnest until mid-October. Some browns will begin moving upriver in late September but it doesn't get hot and heavy on most fall fisheries until the middle of the month. This is also about the time of year when the rivers become empty—most out of state anglers are nervous about coming and having wintery weather and locals are out hunting. Several of the best brown trout runs such as the Madison and Missouri don't hit their peak until late October and even into November. Dress for the Weather Fall weather in Montana is very unpredictable—it can be warm and pleasant or you can receive an early dose of winter weather. If you plan a trip to Montana in late fall you had better be ready to fish in a snowstorm just in case. Bad weather days also can produce some huge trout so you want to be on the water even in foul weather. Browns are notorious for being finicky and preferring cloudy skies. Go Early and Late Although the insect activity over hatches, like the fall baetis, don't peak until after lunch in the late fall, big browns will still often be most aggressive at dawn and dusk and sometimes even after dark. The really huge browns aren't that active in the late morning to early afternoon hours so make sure you dress for cold weather and get out there at dawn and fish after dark as well. Recommended Gear Big alligator mouthed browns often eat trout in the 15" class without a problem. If you are trying to hook up on the fish of a lifetime try slow-stripping some massive rabbit fur streamers—no fly is too big. You may go a few days between hookups but you will increase your odds of hooking up on moby dick. Even though big trout mostly eat big meals, in the fall sometimes huge fish fall for egg patterns. Eggs are simply so high in nutrition that even massive browns will eat them. The key, if you are fishing egg patterns, is that you need to know that fish are concentrated in the runs that you are targeting. Even though a big brown will eat an egg, they won't move as far for it as they will for a 10" streamer so you had better put it on a platter and drift it right to them. Streamers are better for prospecting but egg patterns can be deadly where you know browns are concentrated. Fish Waters That Receive Spawning Runs Some of the largest brown trout in Montana reside in large reservoirs most of the season and are largely inaccessible to fly fisherman for most of the year. These same fish aren't that sophisticated because of the lack of flies they have seen. These reservoir browns will move up into the rivers that feed the lakes in the fall. Most of these fisheries aren't a secret: the Madison above Hebgen Lake and Quake Lake and the Missouri are probably the most well known. There are other runs of browns out of larger rivers into medium sized rivers and creeks.