We had to shovel half a foot of snow out of our rafts before loading gear and launching into a multi-day April float trip in the Northern Rockies. Light snow cranked up to full blizzard as the ramp disappeared around the corner, turning the river to slush and all but killing the fishing. A hard freeze settled in overnight, withering the river but greatly improving the bite. We arrived at the take-out three days later wearing nothing but swim trunks and casting big, dry skwala stonefly patterns over a river that had tripled in size.

Spring often provides the most highly variable weather and fishing conditions of the year. I’ve had more than one April trout trip fluctuate 60+ degrees in the span of a few days. Most parts of the U.S. and Canada that sustain wild trout are capable of such atmospheric anomaly. Don’t let that stop you from planning a spring fishing trip, but pack accordingly.

The most consequential weather, however, at least when it comes to the quality of the fishing, happened months ago in the form of winter storms. As warming temperatures melt the high country’s snow pack, water travels downhill and swells creeks and rivers, sometimes to a critical mass. “Run-off” happens at different times in different places but usually produces many muddy and unfishably high rivers for a month or more. The periods before and after peak run-off can produce some of the best fishing of the year. If your timing is good and you know how to adjust your tactics, you’re in for a good day.

Certain types of streams will be inoculated to the effects of rising water. Tailwaters, spring-fed creeks and certain rivers running out of lakes will maintain fishable clarity, even at ten times their normal flow rate. There comes a time every year for trout anglers when such streams provide the only game in town.

The enormous flush of water acts as a double edged sword for fish coming out of a lean winter. It dislodges huge quantities of nutrients and food, but truly big water sends fish scrambling for the safety of cover. While floodwaters can be dangerous to fish, the biggest aquatic insect hatches occur somewhere on the bell curve of the river’s seasonal rise and fall. Trout and other species typically consume their largest caloric input of the year in this time period on the heels of the lean winter months. It’s difficult to fully appreciate that fact until you feel the distended belly of a portly brown trout squirming with dozens of three-inch-long, still-alive salmonflies.

Bring All the Boxes
Fly anglers often bust into spring intent on casting big drakes, stoneflies and caddis, but those bugs never seem to show up as soon we’d like. And even when they finally do, the trout often don’t take a great deal of note for a while longer—not on the surface at least.

Quite frequently in the spring, trout won’t seem to be taking advantage of adult insects because they are simply feasting on the same insects in their nymphal or emerging stages out of sight—not because they “aren’t hungry.”

While surface-specific fly fisherman can get frustrated this time of year, it’s a prime opportunity for those of us willing to fish below the surface, either with subsurface fly tackle (nymphs and streamers) or with conventional spinning gear.

Somewhat contrary to low-water winter, in spring it’s often a good idea to go big and bright. Large stonefly and mayfly patterns are often needed to imitate the big insects drifting in the current this time of year, but size and flash may be equally important to get your presentation noticed in fast current with limited visibility.

Rising waters will also activate and displace the larger creatures living in a stream. Crayfish, sculpins, minnows and baby trout will be forced to seek shelter in confined pockets of slow current. Larger, carnivorous trout will follow. Active-retrieve fishing—streamers, crankbaits or spoons—can be slow to kick off as trout contend with frigid snowmelt but is worth trying any time, especially once the water temp breaks 40. Hungry, high water trout can be more willing to chase big streamers and lures than any other time of year, so now may be the time to finally lash on that quadruple-articulated, marabou monstrosity gathering dust in the bottom of your pack, or a 6-inch Rapala retrofitted with siwash hooks. Unless you’re planning to keep every fish you hook, ditch the trebles.

Think Transitions
While many trout may still be occupying their deep, slow, overwinter holes, plenty will get on the move as soon as things start to warm up. Cutthroat spawn very early in the spring, followed soon after by rainbows. Browns, brookies and bulls will often spend the cold months near their spawning grounds, waiting to drop back out to lakes or larger streams as the water rises in the spring.

Those spring spawning “New World” trout (bows and cutts) will begin to stage weeks or even months before ascending their natal creeks. Finding transitional water is the key to encountering these fish, because it’s usually either illegal or unethical to mess with them once they’re on redds. Look for seams or deep holes in a main river adjacent to creek mouths. In situations like this, if you find one fish, you’ll often find several.

In systems with lakes or ponds, any inlets and outlets will often be prime in spring. Wherever you encounter the confluence of two rivers, the visible color change between the two converging waters is not to be missed. Even within a single stream, transitional zones are important to recognize between deep, pool-pocket winter water where the fish can hold without expending much energy, and shallower riffles where insects are starting to congregate and hatch.

Like their quarry, most trout anglers start to kick out the cobwebs after the first few nice days in late March and early April. The most prepared, observant and adaptable among them will be richly rewarded.