Pressure is measured in millibars (mb). Around 1013 mb is average; under about 1005 mb is properly low and over about 1022 mb is high. Many anglers swear by falling pressure before a front, and while the science on fish sensing pressure directly is mixed, the weather that comes with low pressure — cloud, wind, mild temperatures and rain — certainly changes how fish behave.
The trend usually tells you more than the number. A steady drop over a day is often more interesting than a reading that's simply low and has been for a week.
How fish react
Carp
Often feed more confidently on falling or low pressure, and drift up in the water or go cagey on high, bright, settled days.
Pike
Can go on a feeding spree as pressure drops ahead of a front, and feed again once it stabilises after.
Tench & bream
Muggy, low-pressure mornings are classic tench and bream conditions.
Perch
Often switch on in the dull, unsettled weather a falling barometer brings.
Why pressure seems to matter
Low pressure normally means unsettled weather: cloud, wind and rain. Lower light and a ripple make fish less wary, and mixing water can raise oxygen levels. High pressure usually brings clear skies, bright light and flat calm water, so fish are more cautious in daylight.
Some anglers believe fish feel pressure changes through their swim bladder. Whatever the reason, the pattern of better sport on a dropping glass is widely reported.
Choosing a location
On falling pressure with a fresh wind, fish the windward areas and open water where fish may be moving and feeding. On high pressure, look at snags, overhanging trees, weed beds and deeper water where fish shelter from the light.
Peg choice
On a high-pressure day, pick a peg with cover in range — reeds, trees, lilies or a snag line. On a low-pressure day, choose a peg that lets you cover more open water and react to showing fish.
Bait choices
Low pressure: fish are often feeding, so a bed of bait, a method feeder or spodded particles can work. High pressure: go smaller and more visual — a bright pop-up, zig rigs, floaters or a small PVA bag.
Tactics
On high pressure carp are often up in the water, so zigs at different depths and surface fishing are worth a go. On low pressure, bottom baits and active feeding come back into play. Pressure jumping back up after a front can mean a short feeding window — be ready for it.
Reading the trend, not just the number
A reading of 1008 mb tells you very little on its own. If it was 1020 mb yesterday and it's sliding, a front is on the way and the next 12–24 hours can be lively. If it's been sat at 1008 mb for four days with steady drizzle, fish have usually settled into a routine and the 'trigger' is gone.
The best windows are often the hours as pressure starts to drop, and the period just after a front passes when it begins to climb again and the wind swings round to the north-west. That second window is short and bright, so be fishing rather than packing up.
Pressure through the seasons
In summer, a long high-pressure spell means heat, bright sun and flat water — think zigs, floaters and early mornings. In autumn, the first deep lows of the year often bring the big hits of the season as fish feed up for winter. In winter, high pressure usually means frost and clear nights, which cools the water, while a mild low with a south-westerly is the day to get out.
Predators and pressure
Pike anglers have long rated the drop in pressure ahead of a storm. Bait fish get unsettled, light drops and the pike get a hunting edge. Perch behave similarly, often switching on for an hour or two in a gloomy spell. Have dead baits or lures ready to move swims quickly rather than sitting it out in one spot.
Common mistakes
Writing off a high-pressure day before you've even left the house. Fish still have to eat, and a stealthy approach in the edge at first light can be brilliant. The other big one is fishing exactly the same way on a falling barometer as on a rising one — read the conditions and change your bait and depth to match.
Safety
A sharp drop in pressure often comes with strong gusts and sometimes thunder. Peg your brolly properly, keep an eye on the sky, and if lightning is close get carbon rods down and off the bank — no fish is worth it.
FAQs
- What pressure is best for carp?
- Lots of anglers like pressure under about 1010 mb, especially when it's falling. But warm water and a decent wind matter at least as much.
- Is high pressure always bad?
- No — it can be great for surface fishing and zigs in summer, and fish still feed early and late.
- Where can I see the trend?
- Our Weather page shows each day's pressure and an arrow when it's rising or falling through the day.
- Does pressure matter more on small ponds or big lakes?
- Weather changes hit shallow, small waters faster, so they often react quicker to a front. Big, deep pits tend to lag behind and react more slowly.
- What about after a storm?
- Once a front has gone through and the pressure starts rising, there's often a short feeding spell before bright, cold, high-pressure weather settles in. Be on it.
- Should I change my bait on high pressure?
- Often yes — smaller, brighter or more visible hookbaits and less freebies tend to work better when fish are cagey.
Put it into practice
Check the 7-day forecast and see which venues have the weather edge for your fish.
Related guides
General advice from widely shared angling experience. Every water is different — it’s a steer, not a promise of fish.