Analysis of my bass fishing diary – Part 10 (Air Pressure)

Analysis of my bass fishing diary – Part 10 (Air Pressure)

This is Part 10 of a 12 Part series in which I share my thoughts, conclusions and overall personal experiences of bass fishing over the past 8 – 9 years from the south Devon coastline. In the remaining parts of the series I will also cover:

Part 11 – Rocks, Beaches and Estuaries
Part 12 – Which type of lure?

Note – Please bear in mind that any conclusions I make in this series are based purely on my own experiences and my diary entries. I am positive that there will be many similarities in the hypothesis of my fellow bass lure anglers, or indeed, just as many conflicting or contradictory observations – I look forward to the debates!

Why 8 – 9 Years? Please go to Part 1 (Tide Heights) where I explain.

The last of the ‘naturally occurring’ elements

Having previously covered factors such as tides, weather, wind, light levels, sea temperature, Moon phases, water clarity and sea state in parts 1 – 9, the final ‘naturally occurring’ element that I note in my diary is the air or barometric pressure.

Without going into things too deeply, the baseline or standard (not to be confused with average as you’ll see below) pressure setting used universally is 1013.25 millibars (Mb). When the air pressure is higher or lower than this it can affect the sea level/height of the tide by approximately 1cm for every 1 Mb difference, either side of the ‘baseline’.

Essentially, higher pressure suppresses (lowers) the sea level and a lower pressure (than the 1013.25 figure) allows it to rise. This is why the Met Office sometimes talk about a ‘storm surge’ when a deep low pressure system (storm) approaches the UK – it means the sea level will be higher than normal, which if coinciding with strong onshore winds and   a spring high tide, can cause flooding to exposed coastal communities.

Pressure readings
Plymouth is the nearest weather station to me that keeps easy to read barometric measurements. The website I use to confirm/corroborate on any given day is here but the excellent ‘Time and Date’ website here will allow you to input the location closest to you.

What does this mean for the bass angler?

Phew! Right back to the fishing and this phenomenon can be very useful to the bass lure angler and, of course, the fisherman in general. Very basically, when the air pressure is very high (say 1030 Mb) and this coincides with a very low spring tide, then the sea level will actually drop even lower (up to 17cm depending on geographical features and wind direction/strength to name only two variables) meaning this is the best time to go out looking for new bass ground that isn’t normally uncovered!

Conversely, if the air pressure is very low and a big high spring tide is expected, then it may render some marks dangerous as the sea level will be higher than expected – or maybe you’ll be cut off when you weren’t expected to be? These are both extremes, but they are definitely worth being aware of.

So what about the bass catches? Do my diary entires point to a specific range in barometric pressure being the most conducive or does it even matter? Have I discovered any patterns in behaviour…

Air Pressure – My thoughts, conclusions and experiences

Below is a table whereby I have collated my diary entries into a simple format, in order to display the percentage of bass caught during the specified barometric (air pressure) measurements:

Devon Air Pressure

The results above form the following conclusions:

  • The very obvious conclusion is that 65% of the bass I/we’ve caught in the past 8/9 years have been when the barometer measured between 1016 – 1025 Mb.
  • After scrutinising the figures for even when I haven’t actually fished, I’ve found that the overall average air pressure figure, each month, between April – December (throughout the last 8 years) is very consistently around 1016 Mb. From this, you would obviously expect that a high percentage of catches would be made immediately ‘around’ this figure and that a lesser percentage would be seen at the lower and upper ends of the scale, for the simple fact that far less bass fishing has occurred when the air pressure is say, 998 or 1032.
  • What is interesting however, is that a whopping 75% of the bass landed have been when the pressure is 1016 Mb or above. I suspect many (including me) would have thought that increased catches would be made when the pressure was lower than 1016 Mb as this might have been associated with strong (possibly onshore) winds, and potentially more unsetteld weather (the preconceived ‘best time’ to fish for bass from the shore).
  • I mentioned it in Part 9 (Sea State) that 70% of the bass landed in 2017 were in darkness – something that hadn’t occurred before, as I didn’t fish for bass at night with lures exclusively before 2017. The reason I mention this is because I only fish for bass at night when the sea is calm and the weather settled. This is far more likely when the pressure is high and it is more likely to be lighter winds (depending the position of the area of high pressure over the UK) therefore, the figures are skewed slightly due to the 2017 figures being added.
Big bass when the air pressure increases
Could the chances of encountering a really big bass from the shore be more likely when the air pressure has either risen or fallen sharply in the preceding 24 hrs? That is what my stats are suggesting…

My experiences:

  • Now this is where it gets really interesting! I have checked my figures and there are three separate patterns that have got me rather excited…
  • Remarkably, there is a very consistent pattern suggesting much larger bass (6lb+) have been caught during/following either a sharp rise or fall to the barometric pressure. A great example is the 8 September last year when the pressure fell by 15 Mb in less than 24 hrs and I caught my PB bass. The days either side saw bass of 5lb and a 4¾lb landed by my clients, which in turn, points to more decent bass being close inshore during this period – no other small bass were encountered.
  • A recent example of the pressure rising significantly (23 Mb in 24 hours) and a big bass being landed was when a client caught a 70cm (8lb) bass, in darkness, on the evening/early morning of 30 June/1 July 17.
  • Another pattern that has emerged is when those ‘red letter’ days do arrive, and you catch not just one or two, but eight, nine or ten bass in a session from the shore. More often than not, this has occurred when there was a slight ‘blip‘ in the air pressure (of maybe only 3 – 5 Mb), surrounded by days when it was relatively stable and much higher than 1016 Mb. This could indicate a weather system moving though perhaps, creating more movement/aerated conditions and the bass taking advantage of this?
  • Yet, almost inexplicably, a similar pattern appears when the pressure peaks. For example – when a gentle increase in air pressure each day has occurred, reaching its highest setting and then gradually drops again over a period of a week – ten days. On many, many occasions, the day when it peaked saw the best bass fishing (certainly in regards to numbers rather than size)… Weird yes, but this is what my figures have shown.
  • All the way back through my diary entries, I can find example after example like the ones above – the most recent being on 13 November when after a run of blanks  I managed three nice bass, in darkness, including a 6 pounder  (I also lost a monster that night!) Something that stood out was the 13 Mb rise in the preceding 24 hrs.
Bass at night
This was one of three very nice bass landed following a quiet spell in relation to my personal catches. Did the relatively sudden rise (13 Mb) turn the bass on that night?

To conclude

Dissecting my diary entries has been an arduous but enlightening task. And when you discover what you think could turn out to be a pattern in behaviour, it makes it all very worthwhile indeed. Clearly, many other factors come into play time and again when it comes to bass fishing, but even tiny little pieces of, what you hope, could be vital nuggets of information could help you catch one.

For me, anything I can do to increase my odds of landing a bass, or assist with the most important aspect of all in fishing, which is confidence, is time well spent. Please remember though, these are just my findings – it isn’t gospel! And as ever, I would be very interested and grateful to know what my fellow bass/lure anglers have experienced.

Thanks for reading,

Marc Cowling



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