Big storm rolling in

Barometric Pressure

Barometric pressure is one of those difficult topics where you know if you nail it, it’ll help you catch big fish, but it’s a tough nut to crack. Read on to see our top Barometric Pressure Q and As.
1. What is barometric pressure?

The air pressure or barometric pressure, as it’s known, in its simplest terms is a pressure on the Earth’s surfaced caused by the weight of the air. This change in pressure is subtle and cannot be detected by humans, although fish can detect the change and have a fairly significant reaction.

2. Understanding the Numbers

Barometric pressure is measured by the change in liquid mercury. When the pressure drops, the mercury falls and when the pressures climbs, as does the mercury.
To keep it strictly related to fishing, when we talk about high and low pressure we are referring to;

  • High Pressure – usually between 1018hPa – 1030hPa
  • Low Pressure – usually below 1014hPa

When we talk about fishing in high pressure, we are referring to the figures above. Anything higher usually comes with extremely high temperatures and the fishing is usually slow.

3. How it effects the fish?

Again, this can get quite complex, but to keep it simple, it’s the weight of the earth’s atmosphere causing pressure on the water’s surface and the pressure affects the fish is via their air bladder.

During high pressure periods (1018hPa – 1030hPa), there is more pressure force on the air bladder causing it to be squeezed in and making the fish feel relaxed and more comfortable. This brings good fishing conditions.

During a low pressure (when the barometer is around 1014hPa or less), there is less pressure on their air bladder causing it to expand and put pressure on the stomach of the fish. This makes the fish uncomfortable and usually results in slow fishing.

4. Changing Pressure

Where high pressure brings good to normal fishing conditions and low pressure brings poor conditions, a changing barometer is when we really want to be out fishing. If you’ve ever experienced an awesome fishing bite, you can probably attribute that to a quick change in barometric pressure (and your mad skills of course).

A quick falling barometer will bring the best of all fishing situations. This happens when the weather changes from clear to overcast, rain and sometimes storms. The fish can feel this change in pressure and will start to get uncomfortable. They can tell this pressure change is coming, so before they rest on the bottom, they’ll feed as much as they can.

This is the best fishing bite you can get, and usually peaks right before a storm because the barometer is dropping at a rate of knots.

To recap;

  • Falling barometer – High fish activity
  •  Rising barometer – steady fish activity 
  •  High flat barometer – good/normal fish activity 
  •  Low flat barometer – the fish shut down

5. Reading a graph

The skills you need here are to be able to look at an Atmospheric Pressure Graph and understand which trends make the fish feed.

Example of a Fast Falling Barometer – Best Fishing Conditions

falling barometer

Example of a Rising Barometer – Steady Fishing Conditions

rising barometer

Example of a Low and Flat Barometer – Normal Fishing Conditions

flat barometer

6. Pressure isn’t the be all and end all

Barometric pressure is just one of many different weather patterns that affect the habitat of fish. It’s not the only weather pattern and sometimes the fishing can be good on a poor barometer.


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