The answer is not a simple one because there are no absolute answers to why fish bite when weather changes. The conditions in the weather do change many environmental variables that affect the fish, and many theories abound as to what, why and when, etc. I'll tell you what we do know.
We know that fish will eat a bait sometimes simply because they are hungry. We also know that they strike a bait sometimes, not because they are hungry, but out of reaction to its movement, shape, and color. They strike to protect their space. We know that fish use tides 100% to their advantage for all of the above. But when something in the weather or environment is in transition (storms coming and going), fish seem generally to react positively.
Let's start with after it storms or rains. Rain has a much bigger effect on saltwater fish then it does on freshwater fish. The main reason is that after it rains, the salinity level of the saltwater will change. Salinity is important to saltwater fish especially flounder, trout and redfish. It is not as important to snook and tarpon however because they can actually live in freshwater. Depending on how much it rains will determine the following five effects on saltwater fish:
- How much the salinity level will change.
- How much the water temperature will change.
- How much the dissolved oxygen content will change.
- How much chemical runoff will be washed into the water.
- How much force will be added to the tidal current.
All of the above all will affect the bite of saltwater fish.
Regarding freshwater fish, only numbers 2, 3 and 4 will have an effect. As far as #5 goes, sometimes it can create a current through creeks, drainage pipe outflows, or even the rise of the water levels of freshwater lakes, ponds or streams.
Usually it is not the rain itself that has the before-or-after effect on the freshwater or saltwater fishing, unless it is a large amount of rain. It is the actual front and the changing of other weather variables just prior to or after the passing of the front that has the effect. During these times there is a 'rapidly adjusting' barometer that changes many water and weather factors. Fishing just before or just after a front usually means a rapid adjusting barometer. The rising barometer that increases pressure can affect the tide by as much as nine inches. Think of the air pushing down on the ocean and not letting it rise, keeping that tide from coming in to its fullest strength.
The opposite applies to a falling barometer -- less pressure makes it easier for the tide to move in and rise.
So you should be fishing before or after the fronts whether it is raining during them or not. During these times the barometric pressure is rising and falling, which is good for fishing. While wisdom is mostly from anecdotal evidence, anglers fishing on a rising barometer say it's pretty good, and on a falling barometer, it's just average, although I have had days where both were good. There is some scientific evidence showing that fishing is poor when the barometer is very high, very low or not moving at all!
Just when I think I have figured something out with fish behavior, the fish change the rules and teach me something totally new. "There are No Rules in Fishing." That is why it is a never-ending learning process. But the more knowledge you have the better angler you will be. That is a fact.
On another note, I personally enjoy fishing in the rain, or when it's cloudy, overcast and dreary. Not because the fishing is necessarily better, but there are less fisherman around! LoL. That's why I love fishing, just for the natural beauty of the places it takes me and the peace it brings while doing it.
SNOOK PHOTO: The Snook in the photo is sitting right in front of my feet, in just a few inches of water. I was trying to feed him baits from about 15 yards away. He would not eat. The snook swims up to my feet in crystal clear water which is only a few inches deep and decides to eat the bait while I am standing practically on top of him. I will never know why! Snook just don't act like that 99% of the time.
Thank you for sending in your question to The Online Fisherman. It is one of those questions where you can decide which theory you think works. It also makes for a great angler discussion.
Captain David M. Rieumont
The Online Fisherman Inc.