Cold fronts are a hotly (pun intended) debated topic in the angling world and their effects on smallmouth fishing range from little to severe. The few scientific studies done on the topic have yielded inconclusive results while anecdotally, experienced anglers from both the fly fishing and conventional fishing worlds swear that cold fronts have a very significant impact on when and how to fish.

We’ll cover what cold fronts are, their potential impacts on fish, and how (and if) to change tactics when targeting smallies on the fly.

Learn more about smallmouth fishing in general with our “Guide to River Smallmouth Bass”

What is a Cold Front?

A cold front is a mass of relatively colder air that pushes warmer out if its way. The edge of that mass is called the “front” and the system as a whole is called a “cold front.” Because cold air is more dense than warmer air, it forces colder air upward as it approaches and settles in.

The periods of a cold front are identified as pre-front (before the front arrives), during the front (the time when the front settles in), and post-front (when the front departs/the air warms back up). Each of these different periods have different characteristics.

When cold fronts move in, they can be characterized by dropping temperatures, wind, and possible precipitation. As the front moves in, the barometric pressure drops and as the front settles in and passes, that pressure begins to rise. After a cold front, you can expect colder temperatures, blue-bird skies, possible wind, and high barometric pressure for several days until the air temperature warms back up.

So how does this effect fishing? Scientists would say based on the little research done that it does not show any significance, but years and years of anecdotal research from anglers suggests that it has a huge effect on where fish hang and their activity levels. 

To understand this effect on fishing, let’s dive into the possible impact that the major elements of a cold front may have on fishing.

Cold Front’s Effect on Smallmouth Fishing

Temperature

The changing air temperature during a cold front is a major element of the weather pattern and we do know that water temperature is likely the primary driving factor in affecting smallmouth behavior. 

Depending on the cold front’s size and strength, air temperature can drop dramatically, which in turn could significantly alter the water temperature. One thing to keep in mind is that it requires a lot more energy to change the water temperature than it does air. This is important because even though the air temperature may plummet, it does not mean that the water temperature will instantly mirror that drop. 

This difference in energy requirements to change temperature in water and air is important to keep in mind. If you feel the air getting crisper or chillier, it will require several hours or most likely overnight for the water to see those effects.

While the water will take the water longer to cool down, it will have an effect on the fish. Temperature has a major impact on fish activity levels and depending on the time of the year, a drop in water temperature could be a very good thing, or a day of tough fishing (more on that later).

Clouds and Blue Skies

Bright, blue skies a day or two after any precipitation is another identifier of a cold front. Typically in the pre-front and during front periods, clouds are common as the weather changes, which can be beneficial for fishing. The lower light conditions slightly limit the fish’s visibility and may be more likely to strike a non-living fly. However, the wind associated with the pre- and during front periods can quickly blow out any cloud cover and particulates in the air. This results in bright, sun-shiny days that could potentially negatively impact bass fishing.

Conventional wisdom across all types of fishing suggests that bright, sunny days after a front make for tough fishing. One hypothesis that I particularly enjoy is that the shining sun “hurts bass’ eyes” and while there’s no way to back up this claim, it still makes me smile. 

Additionally, the bright skies will also allow predators of fish (birds, otters, etc.) to hunt them down easier and consequently, the survival instinct of fish would trigger them to stay closer to cover and limit their activity more. 

So, even if bright blue skies may not “hurt bass’ eyes,” the consequences are the same- likely more limited activity and tougher fishing conditions.

Wind

Windy conditions are another key product in cold fronts that affect fishing. Winds are typically heaviest right before and during a front as the cold air begins to replace warmer air, creating a mix of high and low pressures resulting in wind.

First and foremost, stay safe in windy conditions. Strong winds are dangerous and no fish is worth your safety, despite some of the crazy things anglers do in search of fish.

On a lighter note, fishing can make casting extremely difficult, especially with a fly rod. Fly fishing in the wind can be extremely frustrating but ultimately is a skill we all need to develop. Shorter casts or even side arm casts can help cut through the wind and generating linespeed is paramount.

Wind can sometimes be extremely beneficial to the angler. Wind creates a disturbance on the water, which limits the visibility of the subsurface fish. Not only will they have a tougher time seeing you, but also predators will have a tougher time seeing them which can trigger fish to get on the prowl for food. 

Depending on the river your fishing and how fast the current moves, wind can blow zooplankton on the windward side of the water, bringing the baitfish toward that windward side. In turn, this can draw in smallies that want to feed on those baitfish into those concentrated areas. Fishing the windward side of a body of water can be very productive.

Barometric Pressure

Changes is barometric pressure is another key result of cold fronts. Barometric pressure is the measurement of air pressure in the local atmosphere. Essentially, it’s how much the air in your area is pushing down onto the surface.

This can affect fishing because it is suspected that fish can feel this pressure with their swim bladders, the main organ that helps control buoyancy. The theory is that extra pressure in the air causes increased pressure on the water which makes fish feel uncomfortable or bloated, forcing them down the water column.

Again, no real scientific studies have proven this explicitly, but years of experience suggest its accuracy. During high pressure conditions, fish go deep and we must fish accordingly. 

The average barometric pressure is 29.9 inHg and goes up or down incrementally from there. Low pressure is considered anything under 29.9 inHg and high pressure is anything above. The consensus is that fishing is much better with a falling barometer and gets more difficult as the pressure rises.

During the pre-front stage, barometric pressure is generally falling, which can be very good for fishing as this will rise the fish closer to the surface. During the front as the cold air starts to set in, the barometric pressure rises quickly and continues to rise after the front. 

Some anglers swear by fishing by the barometer whereas others don’t believe it has a drastic impact. Either way, it is another element of cold fronts to consider when searching for smallmouth bass.

Rain

Rain is another element of cold fronts. While not every cold front has precipitation attached to it, rain is a common by product and can affect fishing.

Rain has several major effects on fishing. During a cold front, rain can expedite water temperature changes as whatever temperature the rain is will accelerate the water temperature dip as colder rain is added to the river. Rain also creates a disturbance on the water surface and similar to wind, it can make fish more active and less likely to get spooked. Rain can also stain the water via runoff from the surrounding areas, resulting in less visibility for the fish. Additionally, heavy rains can alter the water levels and flow rates of a river, resulting in changes in fish behavior and environments (depending on the season).

The effect of rain on smallmouth fishing depends on how much rain falls during the front. Common knowledge suggests that smallmouth fishing can be electric with a little rain and from personal experience, I’ve found fishing right before a storm and right at the onset can set smallmouth into a frenzy.

Fishing for Smallmouth Bass Before, During, and After a Cold Front

With all these elements of a cold front to consider, how does it affect fishing for smallmouth? Cold fronts affect smallmouth bass fishing differently during different parts of the year and it’s important to understand how this works- cold fronts can be a very good thing or could mean a tough day on the water.

Spring

Spring time for smallmouth bass revolves around the spawn. Spawning requires a specific set of conditions, including temperature, water clarity, and bottom structure, so bass can be picky about the right conditions.

Depending on the period of the spawn, cold fronts can either positively or negatively affect smallmouth bass fishing because it can impact spawning conditions. With spawning on their minds, smallies will look for those specific conditions in order to do their thing and cold fronts could knock the water temperatures out of those ideal temperatures.  Heavy rains could muddy the water up or possibly transform the bottom structure.

Cold fronts during the spawn can slow fishing down. Fish are laser focused on the spawn and cold fronts can disrupt their spawning cycles. Not that we should be fishing for spawning fish anyway, but you will likely see less fish spawning during a cold front during this time of the year.

Post-spawn cold fronts have less of an impact on fishing than the other times. Post-spawn fish are typically lethargic to begin with, so a cold front may slow them down even more, making for tough fishing conditions. Fishing the pre-front would provide the best opportunity to catch fish. If you’re fishing during this time, go low and slow!

Summer

Summertime cold fronts could be either good or bad for smallmouth bass fishing, depending on the severity of the storm. Summertime brings a lot of stable weather, and smallies (like all fish) love stable weather. If a mild cold front comes in and minimally drops the water temps, it could turn the fish on by giving them slightly cooler, more ideal temperatures for activity. If the storm is severe and drops the water temps significantly, it can disrupt the feeding patterns they’ve grown accustomed to during the more stable summer months.

Summertime is the warmest time of the year which means smallies’ metabolism is at their highest. Even if a cold front passes through, they’ll quickly need to consume calories again in order to offset the calories burned in the warmer water. They may not be in their typical haunches during a cold front, but likely are in slightly deeper water and likely will be on the feed again once the storm passes through.

Fall

Cold fronts during the fall can trigger the feed. During the fall, water temps are steadily declining and smallies can sense the approaching cold of the winter. Cold fronts signal to the fish in a very Game of Thrones fashion that “winter is coming” and they need to feed before the coldness of winter sets in for good.

Winter

Wintertime cold fronts don’t impact smallmouth fishing all that much. Fishing is slow in the winter with the cold water temps, so any drop in already cold conditions won’t sway fishing productivity all that much.

Fish can still be caught in the winter, though conditions are already tough. Slow moving flies in deep water would still be the way to go as fish are likely settled into their winter haunches, but they likely won’t care that the water temp is a few degrees colder than usual. Fish won’t care that the water is 43 degrees instead of 46. Cold is cold!

Conclusion

Despite limited scientific research done to objectively identify the effect of cold fronts on smallmouth bass fishing, years and years of anecdotal research from all types of anglers suggest that cold fronts can impact fishing for smallmouth.

Whether or not it’s the front itself, or the known effect of the elements of a cold front, we need to be aware of frontal conditions when bass fishing. In Fisherman editor Ned Kehde summarized it well when he said “I don’t try to prove causality; I just note how, when, and where I catch each bass and adjust.”

Knowing how the elements of a cold front can potentially affect bass fishing is important to grasp in order to catch fish in changing conditions. A cold front passing through is no reason to stay at home for the day, but might require some adjustments on the water. So get out there and fish!

What effects of cold fronts have you noticed?