Best Barometric Pressure for Fishing

Some experts do agree that fish behavior is influenced by changes in barometric pressure.

While barometric pressure may not directly affect the fishing conditions, it is a major factor that can influence what a fish may be doing at any given time.

What is Barometric Pressure?

Barometric pressure is a measurement of the amount of force the earth’s atmosphere is exerting downward at any given time.

A greater influence of fluctuations in barometric pressure, (the short-term fluctuations that can influence fish behavior) is caused by local weather patterns that involve pressure ridges of air moving across the landscape.

Barometric pressure can be measured in several different units of measure.

The most common official measurement you will encounter is “mmHg”.

So what is a baseline “normal” pressure?

Generally speaking, somewhere around 29-30 inches Mercury is a rough “baseline”, though remember this is also dependent on your elevation.

Higher elevations will have a lower baseline barometric pressure than lower elevations.

It is better to watch your local weather patterns to understand your local baseline conditions.

When a storm system begins to move in, barometric pressure begins to drop.

During a storm, the barometric pressure readings are often low, around 26-29, generally.

After a storm has passed, barometric pressure will begin to rise as calmer and clearer weather takes over.

High pressure is generally associated with very calm, clear, and warm weather. These high-pressure systems can keep storms and low pressure at bay for days on end.

It is hard to physically distinguish “normal” from “high pressure” without an instrument. Generally, “high pressure” can be considered 30 inches of mercury and up.

How Fish React to Changes in Barometric Pressure

Nearly all fish have a swim bladder organ, which is an inflated air sac that helps the fish maintain neutral buoyancy in the water.

This air sac, particularly in small-bodied fishes, is very sensitive to changes in atmospheric pressure.

When the barometric pressure drops, the swim bladder inflates slightly from the reduced pressure around it.

Conversely, when the barometric pressure rises, the swim bladder shrinks ever so slightly underneath the increased pressure.

So what does this mean for the fish?

Think of an inflated swim bladder like a bloated belly, it doesn’t feel too good.

When the pressure drops, fish can get uncomfortable from their swim bladder inflation and seek out a place where they don’t feel this anymore.

By swimming deeper into the water, they can experience higher pressure from all the weight of the water and it will help to reduce the size of their swim bladder to normal.

Now on a normal-pressure or high-pressure day, fish may not feel this discomfort from an inflated swim bladder.

Therefore, they feel comfortable utilizing a larger variety of the water column and are more apt to be active and feeding.

The Best Barometric Pressure for Fishing

So how do you use all this information to better your fishing?

Many anglers will tell you to “fish on the drop”.

They mean to fish just before an incoming storm front, when the barometric pressure is just starting to drop.

The fish can sense the incoming low pressure and know they will have to seek refuge deeper.

This means that they become very active during this time trying to feed as much as possible or moving around to find deep cover.

Once the pressure drops low in the middle of the storm, you can best assume that the fishing may not be stellar.

Much of the fish may be waiting out the low pressure in deeper water, not wanting to feed heavily.

On the other end of the spectrum, the normal to high-pressure days, fish activity can be much more normal and leisurely.

During these times, the fish are not likely to feel much swim bladder discomfort.

Therefore, they are more apt to be cruising around the water body, exploring varying depths, and feeding at a normal rate.

The fishing conditions usually improve several days after a low-pressure system has left, as the first day or two the fish may be acclimating.

Barometric Fishing Chart

WEATHER FISHING ACTIVITY

High Pressure 30.50+ Fish Bite is Medium to Slow. Try fishing slowly in deeper water or near cover.

Medium Pressure 29.70 – 30.40 Normal Fishing. This is the time to test lures, baits, and techniques to see what works.

Low Pressure 29.60 and Lower Fishing Slows. Fish slow and in deeper water or near cover.

Rising Pressure Improving Weather

The fish are slightly active. Fish slow and in deeper water or near cover.

Stable Pressure Fair Weather

Normal Fishing. This is perfect to try different gear or baits.

Falling Pressure Degrading Weather

Best Fishing. The fish are likely to feed on anything.

Monitor Barometer Yourself

To get a better understanding of your local weather conditions, normal barometric pressure, and how pressure systems move in and out, start watching your local weather.