April Fishing on the Jefferson River

April weather, stream flows, and summary

April on the Jefferson River has a dedicated local following of anglers. And for good reason—the river is in pre-run off mode, many of the river’s larger brown trout are actively seeking prey, and hatches of Blue Winged Olives can occur any day. 

Anglers on the Jefferson River will find pocket water, riffles, pools, shallow flats and shelves, deep runs and pools, and plenty of undercut banks. Anglers can enjoy a mix of floating and walk-and-wade fishing on the Jefferson River in April. During April floating can be more effective as anglers can cover more ground and because hatches are sporadic and fish populations are lower than other rivers, a boat proves invaluable to cover as much water as possible. 

Weather on the Jefferson River in April covers a broad range of conditions. Early in April the average daily high temperature rarely tops 50 degrees F, but by the end of the month the average daily high temperature rises to almost 60 degrees F. April receives an average of 1.1 inches of measurable precipitation, with half of that falling as snow and half falling as rain. 

Stream flows in April can be relatively unpredictable due to the possibility of changing weather conditions. For the first part of the month, if cold weather persists, the majority of the high mountain snowpack remains frozen. Because of the snowpack staying frozen, the first half of April rarely sees the river become muddy or too high from snow melt runoff. 

However, the second half of April can be a wildcard should warm weather or rain persist. If daytime high temperatures rise above 70 degrees F and nighttime lows stay above 32 degrees F for more than a few days, snow melt runoff commences on the Jefferson River. When this occurs, it is time to forego fishing until runoff subsides in early June. 

April fishing: what to expect

April on the Jefferson River truly runs the gamut of all angling opportunities…and there is no way to predict which opportunity will present itself. Downstream from the river’s start—the Beaverhead and Big Hole Rivers combine near Twin Bridges to make the Jefferson—fish numbers are the highest. As the river travels downstream for over 60 miles to join the Madison and Gallatin Rivers, trout populations gradually decline. 

If fly fishing the Jefferson River in April, to catch the largest fish it is best to fish streamers. Predatory brown trout actively seek out prey. This may sound exciting, but patience is very important as unlike other area rivers, the Jefferson River has less trout per mile. Most anglers on the Jefferson River cover a lot of water, therefore floating is the preferred means to fish this river. For streamer fishing choose size 2 to 6 streamers in white, olive, or yellow/brown. A sink-tip can be an important addition to any rig. Slowly-stripping or dragging streamers through deep, slow runs or pools will produce more than fishing shallow flats or 4 to 5 feet-deep runs. 

For anglers desiring dry fly fishing, hatches of Blue Winged Olives (BWOs), skwalas, March Browns, and some caddis can occur. Various conditions need to line-up for the strongest hatches to happen, but similar to streamer fishing on the Jefferson River the best way to fish dry flies on the Jefferson River is to commit and hope for best. Choose appropriate dry flies to match the desired hatch. If a hatch does occur target foam lines and back eddy currents. Jefferson River trout in April rarely feed in fast currents, rather they hang out and feed in foam lines and back eddies. 

Where to find April trout on the Jefferson River

Fly fishing the Jefferson River in April is all about fishing the river before snowmelt runoff commences. Once snowmelt runoff begins, typically later in the month or early in May, fishing becomes challenging. However, prior to snowmelt runoff, spring hatches of skwala, stoneflies, Blue Winged Olive (BWOs), and an early Mother’s Day caddis hatch can provide plenty of action. 

Because water temperatures are rarely above 50 degrees before runoff commences—trout will be found in slower currents. Focus on the rivers slower and deeper waters—places like inside bends, long runs, eddy-lines and foam seams around large rocks or other structure. These “softer” waters allow for trout to expend very little energy while having access to available food. 

If hatch a occurs, look for trout to move into feeding lies. In April, hatches of BWOs will most likely make up the bulk of the hatches. For BWOs target slower water near bankside structure or the tailouts of longer, slower runs. If caddis or skwala stoneflies hatch, fish may move to faster water, but because the water temperatures are still cold, even during a strong hatch expect to find fish in slower water.

Fishing streamers on the Jefferson River in April has a loyal following of local anglers. If anglers want to hunt for big fish with streamers they should fish over-sized flies and understand that quality over quantity is the name of the game on the Jefferson River in April. Choose white, yellow, or olive streamers in sizes 2 to 6 and pick an articulated pattern for the most success. 

Important April hatches

In April, on the Jefferson River hatches are sporadic. If the right conditions line-up, hatches of Blue Winged Olive (BWOs) mayflies, skwala stoneflies, Mother’s Day caddis, or March Browns can occur. March Browns and skwala stoneflies are sporadic but prospecting with a March Brown or a skwala pattern can entice a fish to rise. BWOs can hatch on sunny and cloudy days, but a cloudy, slightly rainy day can create a large emergence. 

March browns are not as prolific as BW0s, but the larger size 10-12 mayfly can entice bigger trout to the surface even during a sporadic hatch. Like BWOs, March browns will hatch in greater abundance with overcast skies. 

As the month progresses and local weather becomes more spring-like than winter-like, caddis can hatch in prolific numbers. Most caddis will be size 14 and 16 and are dark bodied. However, as the warmer weather ensues and month’s end nears, the risk of off-colored water and rising flows increases, thus decreasing the clarity of the water and onset of spring runoff.  

Jefferson River fly box for April

Caddis pupae size 12 to 16

Caddis CDC emergers size 12 to 16

Caddis dry flies with dark grey, black or brown bodies in size 12 to 16; 

BWO dry flies size 14 to 18

BWO emergers size 16

BWO nymphs size 16

March Brown dry flies size 14 to 16

Skwala stonefly dry flies in size 8 and 10

Stonefly nymphs in brown and black in sizes 10, 8 and 6

Sculpin patterns in sizes 2 to 6

Streamers in white, yellow, or olive in sizes 2 to 6