Anglers often see barometric pressure as the most powerful natural force that affects fishing.
A high pressure front passing through can mean a quick end to any hopes of having a great day catching instead of just fishing.
But what if it’s not the pressure change that makes the difference?What if the pressure change isn’t even much of a factor at all?
Yes, observations that changes from low to high pressure can coincide with fishing becoming more difficult.
But that doesn’t mean the pressure did it.
Changes is pressure can come with other weather related changes. These forces can combine to have an impact on fish activity.
What Is Barometric Pressure?
Simply put, barometric pressure is the pressure exerted by the atmosphere.
One atmosphere is the pressure at sea level which amounts to 14.7 pounds per square inch(psi). This is also commonly expressed as 1,013.25 hPa.
hPa is short for HectoPascals. A hectopascal is equivalent to 100 pascals. We will user hectopascals (hPa)going forward.
1013 hPa is the average pressure at sea level. So, as you can imagine, there is a variance above and below this pressure.
These pressure changes are where all the fun lies.
You can go from deep lows of 900 hPa or even lower. You can also go to extreme highs of 1050hPa.
The question is what do these changes do to the weather. And more importantly, what do these changes do to the fishing.
The Effects Of Barometric Pressure On Fishing Weather
Generally, low pressure can bring unstable and stormy conditions. Hurricanes are an extreme example of a very low pressure weather system.
By contrast, high pressure can bring clear skies and generally cooler temperatures. They’re not often associated with stormy conditions.
So as you can see it’s very likely that these changes in weather affect both the fish and the fishing. It may even be the case that going from 1013 hPa to 1025hPa doesn’t even phase most fish species.
Even when a storm is fast approaching, the changes in barometric pressure are very small. Of course this is all relative and to a fish it may or may not be detectable.
But what makes me say these changes are small?
Underwater Pressure Comparisons
Water is almost 800 times as dense as air. Changes in depth can have a much larger impact on pressure than a change caused by a cold front.
For example, at 38 feet deep, the pressure is twice what the atmospheric pressure is on land.
So, as you can see, a change of just a few hPa caused by a storm or a cold front is nowhere near that. A large change in barometric pressure can amount to just 20 hPa.
But going from the surface to just 10 feet deep is an increase of almost 300 hPa. Trust me, if a cold front would raise pressure by 300 hpa, it would be all over.
Keep in mind though that if you bring a fish up from deep water of about 20 feet or more, that fish may suffer decompression issues. The fish’s stomach can get pushed out of its mouth by the expansion of air.
But when this happens, we’re talking about a change of over 600 hPa. That’s 300 times more that what happens with a big cold front.
Anyways, so we’ve established that a cold front really shouldn’t have a significant effect on the fish themselves.
Side Effects Of Pressure Fronts On Fishing
The weather changes that come with the climbing barometer are more likely to have a bigger effect.
Changes in temperature along with cloud cover, and wind can have a big impact.
A sudden drop in water temperature can move fish out of the shallows. And this often makes a huge difference in how easy it is to catch fish.
Bluebird skies in which there is ample brightness penetrating the water can make fish wary.
They’ll be easier to spook by anglers making careless approaches.
Additionally, ambush predators such as snook and bass can have a harder time taking their prey by surprise in these bright conditions.
This may cause them to seek out thicker cover, head out deep, or feed more at night.
If you rely on camouflage to do your hunting, then bright blue skies with not a cloud around might be an issue.
Then there’s the problem with your lures. These same bright blue skies that make it easy to see the bass, can make it easy for the bass to see your lures.
They’re more likely to get a good look at them. Instead of a quick glimpse in low light. When this happens, a fish may be much more likely to reject your presentation.
Additionally, these weather changes may be having an even more pronounced impact in the fish’s prey.
Small baitfish that feed on microscopic plankton can more easily be moved by wind and waves. And they may possibly feel more of the effects of pressure changes.
Positive Effects Of Pressure Changes On Fishing
Of course, there is a bright side to all of this.
You may have heard reports of fantastic fishing right before a cold front or before a major storm.
It’s true that clouds and wind can often work in an anglers favor.
Clouds that move in can work in various ways.
They can make it easier for ambush predators to hunt. Reduced light levels can also mask your approach and make the imperfections in your lures less visible.
Lines, treble hooks, split rings, and leaders can all become less visible in low light conditions.
This can help your hook up ratio by itself.
Add to that a nice wind on a point or a shoreline. This can push plankton and baitfish up against structure.
Predators are bound to follow. The combination of waves, low light and prey can make for truly exciting fishing conditions. So, don’t discount them and experiment with conditions in your area.
These types of scenarios can occur before high pressure fronts or low pressure fronts.
So, keep an eye out for bad weather systems and try to catch the feeding that happens before they hit.
After these systems pass, things can slow down dramatically. After a high passes, bright conditions and cold weather can potentially turn the bite off.
After a low, fish may seem to scatter and be more difficult to find.
One of your best bets is to try and find a pattern for the water you’re in.
As you can see barometric pressure is an indicator that can be used to predict weather changes.
But whether it causes fish to turn on or off is definitely not a certainty.
You should definitely use all the information you can get. But trying to understand the underlying reasons for why see certain fish behaviors is your best best.
In the end experience on your waters can’t be beat. Go out there and find out what makes the fish in your body of water behave the way they do.