How Barometric Pressure Affects Bass Fishing
Weather affects bass fishing. This general statement can be agreed upon by the entire fishing community. However, there is much debate over to what extent weather affects fishing.
The majority of what you were told on this subject by your dad as a child or what you hear from other fishermen is simply myth, or personal opinion. Not to say that none of it is true, and in some cases, it may very well be. But the truth behind weather and its affects on fish behavior is a matter of science, and can be explained by examining facts, that have been tested and proven.
There are 6 weather related factors that affect fishing conditions:
- Barometric Pressure
- Cold Fronts
- Warm Fronts
Here we will explore the first weather factor that affects bass fishing, which is Barometric Pressure.
Before you can understand Barometric Pressures affects on fishing, you need to understand what Barometric Pressure actually is. Barometric pressure is the measure of the weight of the atmosphere above us. It exerts pressure on the waters we fish and even on us. Measurement of barometric pressure is accomplished with the use of a barometer. A barometer measures the weight of the atmosphere per square inch (pressure) and compares it to the weight of a column of mercury. A standard Barometric Pressure for most of the U.S. is 30 inHG. Low readings bottom out around 28.5 inHG and highs top out around 31.5 inHG.
The barometric pressure changes as the weather systems over us change. When you look at a weather map that has those blue “H”s and red “L”s, this is indicating the areas with High and Low pressure.
As high pressure moves in, winds shift to a clockwise pattern, blowing away from the center. Weather conditions associated with Spring and Summer high pressure systems are typically clear with dry air and little or no wind. During the fall and winter, high pressure usually brings sunny, clear skies with a cold breeze, and poor fishing conditions.
With the approach of a low pressure system, the wind shifts to a counter-clockwise pattern and blows towards the center of the area. Weather inside a low pressure system typically features cloudy skies, high humidity, slight temperature change and an unstable atmosphere. The unstable atmosphere created by the low pressure area displacing the high pressure area usually leads to precipitation or stormy conditions. Fishing is almost always good during times of low pressure.
Falling pressure is a direct indicator of good fishing conditions.
There are several myths as to what makes bass react differently under different barometric pressures. One being that high pressure makes the fish uncomfortable and stressed, therefore prompting it to seek shelter and not feed. This is not true. The truth is that the falling pressure makes the plankton and invertebrates more buoyant and causes them to float or suspend, making them easy targets for shad and other bait fish. The increased feeding activity by the bait fish in open water makes them an easy target for predator species such as Bass. Bass become more active as a result of their prey becoming more active, and vice versa.
The influence of Barometric Pressure on fishing is greater in shallow lakes, than deeper ones. Deep water has so much internal pressure that the atmospheric pressure has little effect.
Another Barometric Pressure trigger for bass feeding activity is the cloud cover associated with each type of system. Falling barometer is a sure sign of an approaching front, which means cloud cover will increase. The darker conditions associated with cloud cover will make bass more active. Less light on the water makes the fish feel less vulnerable and more likely to cover more area in search of food.
Barometric Pressure has little or no influence on fishing in constantly flowing rivers and streams. The water flow causes constant changes in pressure, reducing the significance of pressure changes on the surface.
Here are a few very general rules for fishing during the changes of Barometric Pressure:
And for those of you who plan to watch the Barometric Pressure, here's a chart that illustrates the fishing conditions associated with different pressure readings.
- Rising Barometer = Better Fishing Conditions
- High Steady Barometer = Fair Fishing Conditions
- Standard & Stable Barometer = Good Fishing Conditions
- Falling Barometer = BEST Fishing Conditions
- Low Steady Barometer = Fair to Poor Conditions
Understanding the effects that Barometric Pressure has on fishing conditions is just the first step in understanding the effects that weather as a whole has on fishing. For more information on the other weather factors, see my other factoids on each topic.