Wouldn’t it be great if all our fishing dreams turned out exactly as we imagined them? Picture this - you’re sitting in your boat on a banner day. The sky is blue, there’s not a cloud in the sky, and the fish are absolutely slamming your line.
Unfortunately, that’s seldom the case.
Wondering what you did wrong? Probably nothing - except not paying attention to the best weather and pressure for fishing. The weather and pressure both affect fish in some pretty unique ways. In this article, I’ll tell you everything you need to know.
What is Barometric Pressure?
Barometric pressure is one of the biggest factors that can influence how fish feed. Sudden changes in the weather can influence abrupt changes in barometric pressure, many of which can create ideal circumstances for opportunistic anglers like yourself!
Barometric pressure, also referred to as atmospheric pressure, is the force that is exerted by the Earth’s atmosphere in a given area. It’s more or less the weight of the air.
It is usually measured in inches of mercury or pounds per square inch. When you’re at sea level, a barometric pressure of 29.92 is considered normal. Higher than that is considered high barometric pressure and, of course, lower than that is considered low barometric pressure. The actual numbers don’t matter as much as how fish are affected by the swings.
During times of high pressure, you’ll enjoy clear skies and calm waters. Medium pressure may be a bit overcast, but not very. Low pressure may produce cloudy or rainy weather - it’s going to be stormy.
How Does Barometric Pressure Affect Fish?
Barometric pressure affects fish in several ways - many of which may intrigue you as an angler. Fish have a series of physical adaptations that help them survive in water. Two of these are impacted by barometric pressure.
The first is the swim bladder. The swim bladder is an organ not unlike a stomach. It can inflate with air and lets the fish become buoyant. When the barometric pressure changes, the pressure on the swim bladder changes, too. Fish with larger swim bladders, like tarpon and trout, are the most sensitive to changes in air pressure. those with smaller swim bladders, like mahi-mahi and kingfish, are less affected. Some fish don’t have swim bladders at all (like tuna) and so they aren’t affected by swings in the slightest.
The other fish organ that is affected by barometric pressure is the lateral line. This organ is used to navigate and to sense the presence of food. It can sense slight reverberations in the water, including waves and changes in pressure.
Even minor changes in barometric pressure can affect the behavior of fish. This is largely because everything in the water floats, is suspended, or sinks. When there are changes in pressure, there are also changes in gravity. This can upset the delicate balancing act in the water, affecting how fish feed and interact while underwater.
Believe it or not, fish are more in tune with their environment than perhaps you are! They can pick up on minor changes in the pressure and will adjust their behaviors accordingly. It’s important to note that even large fish with small swim bladders are still affected by changes in barometric pressure - even if not directly.
Everything in the water exists as a chain reaction. If there’s a slight drop in pressure, small sediment may float up off the bottom of the lake. This can cause the water to become cloudy and reduce visibility.
Plus, fish that are very sensitive to fluctuations in pressure go into hiding when the pressure changes, the fish that prey upon them are going to feel the effects, too. It won’t take long for larger fish to react to the pressure, even if it has nothing to do with their sensing of the pressure.
When weather comes into play, it's always best to rely on your fishing tools that can help you determine where they're hiding, or the effects that the weather is playing on their behavior that day. A great tool for scouting spots and watching fish is an in-line underwater fishing camera. Take the GoFish Cam for example. You can tie the camera on your line and drop it down on places you think there might be fish. You can also check out how they're reacting to certain baits or lures, if they're extra sluggish in their movements, and how they're behaving that day.
Wind can play a major role in the pressure and temperature of the water - and also on how it affects the turbidity of the water. When wind pushes across the surface of a body of water, it makes waves - you know this already. However, as the wind blows along the surface, it creates friction, increasing the number of waves and influencing the way fish behave. Winds also create changes in barometric pressure, as mentioned above.
Water Temperature and the Weather
Water temperature, as you might expect based on common sense alone, is heavily influenced by the weather. Because most fish species are cold-blooded, they can’t regulate their body temperature.
Therefore, as the weather causes swings in water temperature, the fish will need to adjust their metabolisms and will change their behavior as a result. Water temperature can change in a variety of ways. Of course, there are the slow, seasonal swings that are influenced by the amount of sunlight the water receives.
In most cases, something as small as a passing cloud or even heavy cloud cover won’t change the water temperature. Rainfall, though, will. After all, lots of fresh water is pouring rapidly into a body of water and changing its temperature.
Cold water? The fish will probably slow down. They won’t need as much food to support their daily activities, so they’ll be less active feeders, too. In warm water, however, fish will be much more active, as they will need more calories to survive.
Water temperature affects fish in other ways, though, too. For example, fish need to extract dissolved oxygen from the water into their gills in order to breathe. Believe it or not, the dissolved oxygen content depends heavily on the surrounding water temperature. Generally, cold water has more dissolved oxygen, while warm water has less.
The impacts of water temperature will vary depending on the species of fish. Each fish species has a minimum water temperature that serves as a cut-off for when and if it will feed. Over a certain temperature, and you’ll notice problems, too.
What is the Best Weather for Fishing?
As you can see from the information above, the barometric pressure and weather affect how fish feed and behave! But what does this mean for you, as an angler?
When barometric pressure rises, it generally indicates that the weather is improving and clear, sunny skies are on the way. When it drops, that’s a sure sign that a storm or a cold front is coming.
Fish bite slowly (on average) during times of high and average pressure. You may need to fish areas of cover or in deeper waters when pressure is high. During times of low pressure, fishing will be quite slow. Again, fish are more likely to be hanging out in deep water, but you’re going to have to go after them slowly.
Fish will be most active when pressure is falling, but you may also have some success during times of rising pressure. If you have the opportunity to fish when the barometric pressure is rapidly dropping - like when a storm is blowing in - you’ll have the best results.
Dropping pressure will cause the fish to keep biting when the weather starts to change. Rapid drops in pressure are the best - particularly if the change is more than 0.18 Hg every three hours. Slower drops in pressure can be good for fishing, though, too. As the air pressure rises and begins to stabilize, though, your results will be less pronounced.
Fish are least active when the barometric pressure is stable. They’ll come back out after about three days of steady barometric pressure, though, so be patient. Don’t forget that some other weather-related factors will influence how well the fish bite, too. Generally, fish will be more sluggish in cold waters. That’s not to say that you can’t catch fish - you will just need to use slow-moving baits in order to be more successful.
Similarly, in warm weather, you’ll want to use faster baits. Wind and rainfall can also affect your success. When the water is more turbid, the fish won’t be able to see as well underwater. They’ll rely more on their lateral lines to find food, so you’ll want to use quick, fast-action lures to grab their attention. Try fishing in deeper waters during drought conditions, too.
Just Make Sure You Fish Responsibly
When you’re fishing during conditions of dropping barometric pressure, there’s a good chance that foul weather is on the way. Make sure you read the weather reports carefully and give yourself plenty of time to get to shore safely in case a storm picks up. Also, pay attention to local regulations. Some areas limit the times in which anglers can be out on the water - both for your safety and to level the playing field for the fish. Take these regulations into consideration before casting a line.
However, you can easily take advantage of all weather conditions to catch a ton of fish. You might just want to download a reliable weather app and invest in a good rain jacket!
Thank you Sean Ward from OnTrack Fishing for writing this great piece!