Barometric pressure, or the pressure of the atmosphere on the Earth, can influence many animals, including us. Most often, it just means our knees or joints get achy with bad weather. But what does it mean for trout? Well, for starters, here’s the level of barometric pressure best suited for trout.
The best barometric pressure while fishing for trout is between 29.70 and 30.40 atm (atmospheres), or between fair and clear weather. Low barometric pressure, often attributed to bad weather, is recorded as 29.60 atm.
If you’re like me, then this answer probably raised more questions than answered.
Questions like, “Can I still fish during low barometric pressure?”, “How long should I wait for bad weather to pass before trying again?”, “What’s an atm?”.
Let’s try to answer these and take a further look at what barometric pressure means for trout.
How barometric pressure affects trout fishing
| Weather | Pressure | atm | Behavior | Lures/Bait |
|---|---|---|---|---|
| Cloudy/Rainy/Snowy | Low | <29.60 | Slows down and head to deep water | Bait or none |
| Fair | Medium | 29.70-30.40 | Starts to move to shallows for food | Any with slow to medium speed |
| Clear | High | >30.50 | Biting | Any speed |
Trout, like most fish, prefer high barometric pressure, which is often associated with good weather. When low pressure does come around, their body tissue and some organs, like their bladders, expand. When this happens, trout are known to stop biting and head to deeper water for comfort.
Why do trout get uncomfortable with low pressure?
If you’ve ever had achy joints before a heavy rainstorm or snowstorm, or know someone who has, it’s usually because of the drop in air pressure. If it sounds odd to get achy because of low pressure, you’re not alone. When I first came across this, I thought, “Wouldn’t high pressure be more painful since it’s pushing down on you?”.
But it turns out the high atmospheric pressure is great at keeping our skin and bodily systems in place. When there’s low pressure, there’s new room for the body to expand. So, what are the first things to become uncomfortable when they expand? The parts of the body that have natural spacing or air between them and the rest of the body. Usually, this includes joints, bladders, and sinuses.
Like us, trout can get uncomfortable when heavy rain or snow comes around. They’ll take off into the deeper water, which uses the increase of the water pressure to dampen or add a barrier between them and the lowering air pressure.
However, if trout sense the pressure is going to drop soon, they’ll try feeding before waiting out the storm. If you can time it right, you could land a good catch.
Once the bad weather has passed, the trout will be a little sluggish coming out of the deeper water. If you’re fishing around this time, keep this in mind and use slower lures or bait until they recover.
If the weather has improved, either back to normal (or close to it), you can use a variety of lures and baits and likely find they’re biting again.
How barometric pressure is measured
Barometric pressure is measured in atmospheres (or atm for short). 1 atm is the equivalent to the air pressure at sea level with a temperature of 59º F (15º C).
While this doesn’t help much on its own, you can measure atms with a barometer. I recommend getting a fishing barometer to help keep an eye on the weather.
You can find this one for about $32 on Amazon (which you can find here). It’s also battery-powered, so it’s portable if you want to take it and check conditions on the go.
What is considered low pressure
Atmospheric pressure starts to become “low” at 29.60 atm. At its lowest (during a hurricane for example), barometric pressure can read around 27.30.
When it comes to fishing for trout, know that this drop in air pressure occurs shortly before the storm. So even though you could still be fishing ahead of the storm, the trout are probably already heading to deeper waters.
During the storm, you could still try fishing, but chances are even if you can locate the trout in the deeper water, they’ll probably be too uncomfortable to feed and won’t bite.
At times, you can wait out the low barometric pressure and continue fishing soon after. Other times you can try but you won’t catch anything. This could be because the trout feed heavily before the storm and are still full and sluggish shortly after. But there’s only one way to find out fishing in bad weather works in your region–get out there and try.
What is considered high pressure
High barometric pressure is listed as reading 30.50 atms or above. Often times, this higher pressure occurs on clear skies and good weather. This is when trout are most comfortable (as long as the water temperature isn’t too hot or cold).
At high pressure, you can find trout moving from the deep water into the shallows to look for food. Depending on the exact conditions, trout usually bite slow to medium in this weather, but if conditions are near perfect, trout will be very active.
You can try fishing with most speeds of lures and bait, but keep in mind trout will often seek cover more actively on days with clear skies to avoid predators. Look for them in banks, under fallen trees or bushes, or any man-made structures.
Which bait and lures to use for trout during low barometric pressure
Some good choices for bait and lures for trout in low pressure would be just about any rig that doesn’t move as much. This means you should probably put away your faster lures and opt for a slower one, or even better–use a scented bait to help the trout sense it in the rough weather.
Here are some ideas for bait that can work well with low air pressure:
- PowerBait (bright colors like orange or green work best)
- Garlic corn
- Nightcrawlers
- Grasshoppers
- Salmon eggs
In low barometric pressure, bait will usually work better than lures since you can easily reach the deeper water where the trout will be. Also, using bait is about the slowest moving option when it comes to rigs as you can simply sink the bait and let it sit off the bottom. If your hook and line are disguised well enough, even a slow-moving trout won’t pass up on an easy snack. Consider using a fluorocarbon leader to help hide the line and shape the bait to hide the hook if you can.
If you’re thinking about using a weighted bait, the only trouble with that is trout are pretty smart and will be able to sense if there’s a weight on the line. So, for best results, use a barrel swivel about 1-2 feet above the bait and a bullet weight above the swivel (the bottom half could be the fluorocarbon leader if you want). The bullet weight will help the bait sink, but won’t provide any resistance if a trout decides to test the bait. It will simply slide up the line and won’t alert the fish. For that reason, split-shots are a hard pass with most bait rigs.
Related questions
Is it better to fish for trout before or after storms?
As the barometric pressure drops, trout will often feed to get a last meal in before waiting out the storm. If you can time it right, fishing before the storm could get you a nice catch. After the storm, trout can be full and might not bite. Either way you choose, your safety comes first.
What type of weather is best for trout fishing?
The best weather to fish for trout is on a fair to clear day when the water temperature is between 34-67ºF. On hot days trout will retreat to deeper water, but can still be caught if your lures and bait are deep enough.