Much has been made over barometric pressure when fishing and hunting. But does it really affect animals and their behavior? Is it pseudo-science? And if it really does have an affect, what is the best barometric pressure for fishing?
The Short Answer
The absolute best time to fish is going to be when the barometric pressure is currently falling. The fish will be on the move from the weather that generally accompanies incoming low-pressure systems. They will be quickly feeding, or gorging, on nearly anything they can find, in an instinctual drive to pack on calories for a period of expected low levels of feeding.
The baseline “normal” range for barometric pressure is about 29.8-30.4 inches of mercury or inHg. Barometric pressure decreases with increases in altitude, so your local normal may fluctuate an inch or two to either direction depending on where you are located. This “normal” range would be ideal for a control situation where you try new baits or techniques, and you do not want the weather to be considered a factor in success or failure.
What exactly is barometric pressure?
Barometric pressure is just another term for atmospheric pressure. It is a measurement of the force created by the weight of the atmosphere. This is highly dependent on altitude, for example, the barometric pressure in Denver on an 80-degree day will be much lower than that of the same 80-degree day in Salt Lake City.
Despite remaining fairly constant, there are some weather conditions and patterns that can cause barometric fluctuation. Weather patterns create differences in atmospheric pressure as they move across the nation, and those changes in pressure can also create barometric fluctuations.
High-pressure systems are generally characterized by clear skies or very high altitude wispy clouds, dry weather, and still air. A low-pressure system will bring stronger winds, cloudy skies, and usually some form of precipitation.
Since weather tends to move from areas of high-pressure to those with low-pressure, if you live in a predominantly high-pressure area, you probably do not see a lot of severe weather. The opposite is true for areas of lower pressures, they seem to have constantly changing and shifting weather, which can often include a lot of precipitation, and frequent thunderstorms.
How is fishing affected by barometric pressure?
Experienced anglers already understand a significant portion of fish behavior in response to weather, but barometric pressure is often overlooked. With proper monitoring and attention, barometric fluctuations can precede your weather indicators, and allow you to know how the fish are behaving on a macro scale, at any particular moment.
Biological signals – How The Fish Swim Bladder Triggers Their Activity Levels
Barometric pressure causes changes in fish on a biological level. They can literally feel the change in pressure in their internal organs. The vast majority of fish, all sport fish really, have an organ that is called a ‘swim bladder’ that helps fish maintain buoyancy, balance, and proper movement. Not only does the bladder help the fish swim properly, but it is one of the main mechanisms for driving a weather-based feeding cycle.
This cycle is crucial in predator-prey relationships. The swim bladders are much more of a significant factor in small to medium fish, though large, predatory fish generally follow the same behavioral models, however, since their prey is often more heavily influenced by air bladder swelling.
These bladders are a built-in weather station for fish. As the barometer falls, the air in the bladder swells, putting pressure on the rest of the organs, and causing the fish discomfort. This triggers a feeding and shelter instinct in most fish. They sense incoming bad weather, which disrupts food availability in shallower waters, and so they begin to move to deeper, safer water, and they urgently eat anything along the way. As they move to deeper water, they increase the water pressure around them, shrinking their swim bladders and making them feel more comfortable at that depth.
When the pressure finally bottoms out and the weather moves through, the rising pressure causes the reverse to happen. The swim bladders become over-pressurized and uncomfortable again, so the fish will seek relief by moving back to more shallow waters from the sheltered depths they were at. They will be feeding as they move shallower, but the bite will not be as hard as when they are running deep.
Knowing how the barometric pressure affects fish physiologically is key to knowing if the bite is on, off, or in-between.
Which Fish Are Most Affected by Barometric Pressure? (Your mileage may vary)
As we mentioned, not all fish are affected by their swim bladders to the degree that others are. Baitfish like minnows and shad, and small to medium game fish like perch and bass will all move deeper on falling pressure. They will feed like crazy and will strike on just about any bait you drop in front of them.
More predatory fish, walleye, pike, muskies, gar, and sturgeon, will all follow their prey of choice, so as the pressure drops, they will move deeper as well. However, as they are not as susceptible to the effects of the swim bladder, they will be following the other fish, and will not be on the leading edge of the barometric movement, but the trailing edge.
Once the other fish feel the change in the pressure, they will begin to move, then the predators will follow after a short time.
What Bait or Lures Should I Use For Different Barometric Pressures?
While fishing on a falling barometer is definitely the best time to get your baits wet, followed closely by the period of rising pressure after a front, you can also have lots of success in other scenarios by fishing more effectively in relation to the weather and atmospheric conditions.
Falling Barometer (transitioning from high to low)
If the barometer is falling, it is time to get out some fast lures. Diving baits, rattle baits, and anything with a flash or a spinner on it are likely to start a chase and produce a strike. This is a scenario where you can probably save on the live bait and just stick to plastics and other artificials, since the fish are going to be feeding so enthusiastically, they will not prefer one over the other.
Low-pressure fishing takes a lot of the mystery out of finding fish because you already know they are going to be hanging out in the deeps. The problem is, they probably will not be open to feeding much, because in inclement weather the bite generally shuts down for a lot of species. Even species like walleye that may feed more heavily in overcast or cloudy skies are slowed down during turbulent weather.
Being effective in low-pressure systems means using slow baits and putting it right in front of their face, working it very slowly and deliberately. A jig just large enough to feel the bottom, with live bait like a worm, minnow, or even a leach, would be a great set up. Plastics and other artificial baits are unlikely to get much action in these conditions. The more natural “prey in distress” live baits are going to be your big producers.
High-pressure systems trending upward are going to produce active fish, though not as active as a falling pressure scenario. You will be able to pull largemouth and smallmouth bass from the shallows, around downed trees, and other sporadic structure. All sorts of perch, crappie, and other panfish should be accessible, and walleye can be taken off of ledges and structure between deeps and mid-depth. Once the pressure plateaus, the bite will cool and slow significantly.
What is the best barometric pressure for bass fishing? (and the best baits)
Bass bite best on the first hint of falling pressure or worsening weather. They turn on when the barometric pressure begins falling, and will feed voraciously on surface baits, diving baits, rattling baits, and spinnerbaits.
If the pressure is stable or holding steady in the normal range, you can use any standard bait or techniques. This is the perfect time to practice new methods or learn to use new lures or baits without the weather being a factor in determining success or failure.
Rising pressure means the weather is getting nicer out, and the bass will be moving from the deeps to the shallows. They will become active to a certain extent, and while they will not be as aggressive as when they are on the leading edge of a storm, they are certainly more active than during steady low pressure.
What is the best barometric pressure for crappie fishing?
Crappie are affected by barometric pressure just like most other fish. While they feed the best on falling pressure, they can display some other behavior that is unique to them. This is particularly true for periods following barometric changes. Crappie tend to be very sensitive to the pressure changes, and they are known to turn off for a period following the changes.
For example, they will feed heavily during falling pressure, then when the pressure has bottomed out an is low and steady, they will reduce feeding. They then become slightly more active on the rising pressure, turning off again for a while when the pressure plateaus.
Low pressure can often cause crappie to suspend in mid-depth ranges, and whether the pressure is low or high, if it is steady for a few days the crappie bite will start to ramp up again. Very high-pressure scenarios with bright and sunny skies will often see the crappie looking for relief in the shade, or in a little bit deeper and cooler water.
What is the best barometric pressure for ice fishing
Fishing in the winter months is challenging. Not only is the environment colder and more challenging to fish in, but the behavior of fish is also much different than during the summer months. In the summer, energy levels are high, food is plentiful, and metabolisms are revved up. As the seasons turn and the weather cools, the metabolism of gamefish slows considerably.
They move less, expending less energy, and so they need to replace less energy in turn. So even in ideal conditions, fish will be much less likely to aggressively hit any bait, since it is not an economical use of energy. This means that once you identify the best barometric conditions for ice fishing, you will still need to adjust your techniques and expectations to be in line with the reduced drive to feed. Basically, your bait has to be slow and close in order to interest a fish under the ice.
Barometric pressure certainly has its effects on fishing overall, since water is very nearly incompressible, and when lakes or rivers freeze over, these effects can be magnified by the ice cap on the water. The food supply in winter is much different than during the height of summer and does not often cause much movement en masse, the fish will still move just to a lesser extent. The pressure changes that occur with fluctuating barometric readings can cause fish in ice fishing scenarios to change their depth in response in order to remain comfortable.
When the weather begins to worsen and pressure falls, fish will be more likely to change depth and move to slightly deeper water to compensate. Following a significant change in pressure, feeding behaviors in cold weather can often be suppressed for a day or more while they reacclimate to their new depth and pressure. Once this re-acclimation period has passed, normal feeding will begin to pick up again and should remain steady while the pressure does.
The best barometric pressure for ice fishing is the pressure that maintains a bit of a plateau for you, allowing the bite to warm up after atmospheric changes. If a storm just passed and it is expected to be steady pressure for a few days, that is a prime time to hit the ice. The same goes for a storm or front that is expected to move in and stay for a few days, the bite will turn off while the weather comes in, but then you can get the tackle box and ice fishing gear out and bundle up, after a day or so the fish will begin to feed again.
Tracking barometric pressure yourself
Here’s a quick reference with the average numbers.
- High pressure (30.5+ inHg) – Clear bright skies. Slightly active bite in medium deep cover. Shallow dwelling fish like bass can be prolific.
- Rising pressure – Weather is getting better. The fish will be slightly active, found around the deep and mid-depth structure.
- Stable, standard pressure (29.8-30.4 inHg) – Normal fishing conditions. Great time to test out or learn new lures or techniques.
- Falling pressure – Weather is getting worse. Best time to fish. You can throw any bait you like, and you will probably be able to get some strikes.
- Low pressure (29.7 inHg or less) – Cloudy skies and rainy. Slow to no bites. Fish slow, in deep cover. Walleye are more productive than other species in low light.
There are a large number of handheld barometer options depending on the functionality you want and the degree of technology.
There are simple and rugged handheld units that offer basic barometer functionality, and have colored or otherwise noted ideal ranges. These can be clipped to a fishing vest, clipped onto the console, or worn on a lanyard. Common favorites are the Trac Outdoors Fishing Barometer
There are also handheld digital units that often combine other features, like GPS, compass, altimeter, and so on. Some even found in “survival” or outdoor watches, these units will often show you the current barometric pressure and the direction, but you will need to know your pressures since they are a digital readout and not a color-coded gauge. These often will include a carabiner or built-in handle for tying a leash or lanyard to.
If you are somewhere with cell phone coverage and a data connection, fishing apps are another option. Nearly any weather app will have live barometric readings from a local weather station and will tell you if it is moving or steady.
There are a number of apps that allow fishing data to be shared in a social setting, and many of them include current conditions feature that will report atmospheric pressure data. Examples of popular apps are Fishidy and Fishbrain.
How To Make a DIY Fishing Barometer
You can make a simple barometer in a pinch. It will not be very useful in a scientific measurement sense, but it is a great way to demonstrate the principals of atmospheric pressure.
You will need a 12oz. glass soda bottle and an 18oz. glass jar, some water, and food coloring.
- Make sure your glass bottle and jar are washed, clean, and dry. Be sure to remove any and all labels.
- To assemble the barometer you turn the bottle upside down and set it inside the jar while inverted. You will then need to fill the jar with water deep enough to cover the first inch of the bottle.
- You can then color the water an easily visible color, and tilt the barometer back and forth slightly to allow any air bubbles to go.
- Mark the water level with a rubber band. Add additional bands for low and high-pressure systems. Store in an area that will not see direct sunlight or artificial temperature variation, or where it is likely to be tipped over.
Do fish bite better on a rising or falling barometer?
They bite harder on a falling barometer. It is also easier to manage the fishing window on a falling barometer, as you may have a window of 4, 6, or maybe 8 hours before the weather or the storm hits, in which the pressure will be decreasing. This is an easy window to plan your fishing in.
You can get strikes by working your bait of choice parallel to the shore at a set depth, or by casting shallow and working toward deeper water.
Once the front has passed, the pressure will start to come up, but it will not increase at the same rate by which it fell. Following a low-pressure system, it could take 12-24 hours before the barometer climbs back up to normal. This depends heavily on the severity of the system, your location, et cetera.
The fish will be feeding during this period of rising pressure, but it will be a hesitant feed. On rising pressure fish can be pulled by working slowly and deliberately, from deep to shallow, imitating their food that is moving from deep to shallow water.
What barometer is best for fishing?
A big portion of this answer will be up to personal preference, but if your onboard electronics cannot show you barometric data, there are a few different options for you.
If you prefer a weather station style, which will give you not only the barometric pressure but also wind speed, humidity, and other data. There are also small clip-on weather monitors that show you much of the same data in a convenient style that clips on your fishing vest easily. There are even watch types that can keep all the pertinent weather info at your fingertips. If you operate a boat solo and often need both hands, the barometer and weather info watch is a great option.
Is it better to fish before or after a storm?
If you know a storm is coming in, that means there will be a period of falling barometric pressure preceding it. This is the best fishing–get out there and hit the water! Find a spot where you can reach both shallows and deep waters, and fish from the shallow to the deep to imitate prey.
The entire period of falling pressure that precedes a cool front and a low-pressure system can be productive fishing weather.
If you choose to fish an incoming storm, make sure you do so safely. If you are in a boat, you are the tallest object for quite some distance, so get off the water before lightning can make itself a hazard. One sure sign that it is time to put the rods away and head for port, is that right before the lightning begins, the air becomes highly charged with static electric potential, and as your rod moves through the air a monofilament line will make a crackling sound.
Once the storm has passed, you can also fish the back end of it. Once the pressure begins to rise again, there will be a period of 12-24 hours after which the bite will resume at a slightly less enthusiastic level than before the weather rolled in.
How do you read a barometer?
How you read a barometer will highly depend on what type of barometer it is. On an analog barometer, it will probably default to a unit of inches of mercury or inHg. It will indicate the current pressure, usually somewhere between 29 and 31 inHg. Some of these are further simplified by having color-coded regions to denote normal range and extremes.
If it is a digital barometer, you likely have the option to display the pressure in various units. Options on a digital barometer may include the SI standard pascals, millipascals, millibars, or inches of mercury. Once you set it to the unit you prefer, it will display in your preferred unit going forward.