Barometric Pressure, Our Region, and Fishing


As you may know, barometric pressure has a significant influence on wildlife (mainly fish) feeding habits. As I have began to incorporate more predictable factors into my fishing plans (barometric pressure, overcast, etc.) I have a question I need some help on. What is considered high, low, and normal barometric pressure for our region? This would help me greatly as my research via the internet has not provided me with the answer I desire. Thanks for your time and I look forward to your response.


Since I admit that I am not a fisherman, let me open with the fact that MANY fisherfolk (ladies & gents) tell me otherwise, but I have never found any science literature that shows a STRONG relationship between barometric pressure (on its own merit) and fish habits.  Now I also admit I haven't looked in a number of years.

Since fish use variable pressure in their internal bladders for swimming and changing depth, etc. .. they would adapt to even the most minute change in pressure of the water column much faster than air pressure actually changes in nature.  In effect, fish because adapt quicker than the air pressure changes, they wouldn't even notice the modest impact.  (As an FYI, my original training is in bio-climatology ... looking at how weather and climate affect organisms.  Although my areas of specialty were birds and insects -- no longer .. that was a LIFETIME ago -- in the past I did a little digging into the "fish story" as well.)

If you think about it, it does make some sense that pressure alone would have little impact on submerged critters.  While changes in barometric pressure may have some impact on air-breathing animals, and also some impact on the surface of a waterbody, the density of water is SO MUCH greater than the density of air, that even a large pressure chance is unlikely to be detected in a water column more than a few centimeters below the surface  (Okay, short of the tremendous changes that might be generated by tropical-storm/hurricane intensities, which will actually cause a measurable change in the height of the water column).

However, we must remember that changes in barometric pressure are directly related to changing weather, including (1) temperature, (2) cloud cover and (3) winds.  And all three of these are likely to greatly impact the feeding activities of fish .. and birds .. and deer .. and just about every type of wildlife.

What significant rises or falls in pressure do reflect is the first sign of changing weather.  Why do I say "significant"?  Because the pressure typically changes each and every day during the day ... often max'ing during the pre-dawn hours (coolest part of the day) and dropping to a mid-afternoon low (usually the warmest time of the day).

Significant drops in barometric pressure (say, falling from the 30s to the 29s in "inches of mercury") reflect the approach of storm systems and fronts (both are zones of "low" pressure).  Rising pressure is often - although not always - associated with clearing skies and pleasant weather.

Lastly, what really matters in terms of significant weather changes is the amount and rate of pressure change, not the absolute pressure values themselves.  In other words, a change from 30.20" to 30.00" is likely to have the same impact as a change from 30.00" to 29.80" from a pressure perspective.  A change of a couple of tenths of inches of mercury is substantial, especially if it occurs in a period of a few hours.

So .. my thinking is that there is an indirect link between barometric pressure and fish activity .. a reflection of the changing weather properties such as temp, winds and clouds.  I think if you track these elements, I'll bet that you will have equal - or even greater - success than tracking pressure.

Just one guy's opinion ...

Jay Grymes
Chief Meteorologist
WAFB Storm Team