Rain and fishing: before, during and after
Explainer · Last reviewed 2026-08-14
Three different situations that are routinely collapsed into one question, with different mechanisms behind each — and in fresh water the largest effect of rain has nothing to do with the rain itself.
THE QUESTION 'IS RAIN GOOD FOR FISHING' CONTAINS THREE QUESTIONS and the answers are not the same.
BEFORE RAIN. The claim that fish feed hard ahead of rain is one of the most widely held beliefs in angling and among the least well supported. What actually precedes rain is usually a set of correlated changes — falling pressure, increasing cloud, rising or shifting wind, and often warming or cooling air. Attributing the result to the approaching rain specifically means picking one variable out of four that moved together, and there is no good basis for doing so. The honest position is that conditions often do improve before a front arrives and that which of the several simultaneous changes is responsible is not established.
DURING RAIN. Several real and separable effects.
SURFACE DISTURBANCE breaks up the view from above and reduces light penetration, which has the same consequence as cloud: fish will use shallower and more open water.
TERRESTRIAL FOOD IS WASHED IN. Insects, worms and organic material enter the water from banks and vegetation, and in small rivers and streams this is a genuine and immediate feeding trigger.
OXYGEN AND TEMPERATURE change slightly at the surface, which matters mainly in hot weather when a shower cools and aerates a warm surface layer.
HEAVY RAIN COLOURS THE WATER, which helps species that hunt by scent and displacement and hurts sight-hunters.
AFTER RAIN. In stillwater the effect is modest and short-lived. IN RIVERS IT IS THE LARGEST CONDITION EFFECT THERE IS, and it is not about the rain: it is about the resulting change in level, flow, colour and temperature — the spate. That has its own record because the rise, the peak and the fall are three different fisheries.
WHAT IS SECURELY ESTABLISHED ACROSS ALL THREE: reduced light and increased colour change fish behaviour in predictable directions, and a change in river level changes everything. What is NOT established is the specific predictive value of rain as an event, separate from the light, flow, temperature and pressure changes that come with it.
AND THE ANGLER'S SIDE. Rain makes banks slippery and unstable, makes rock and platform treacherous, reduces visibility, and accelerates heat loss dramatically once clothing wets through. In an area with any catchment above it, heavy rain also means the water may rise while you are standing beside it — which is the mechanism behind a substantial share of freshwater fishing incidents.
Where rain is an event rather than a season
The effects above — the freshet, the colour, the extra food, the oxygenation — assume rain arrives often enough to be a condition rather than an event. Across southern Europe and North Africa it is not, and the consequences run in a different direction.
IN A SEMI-ARID CATCHMENT, RAIN IS A FLOOD OR IT IS NOTHING. Long dry periods reduce a river to a chain of disconnected pools with the fish concentrated in them, and then a storm on high ground sends a pulse down a channel that has had no water in it for weeks. That pulse is not a freshet. It carries the accumulated sediment and organic material of the whole dry period, it can arrive hours after the rain and many kilometres from where it fell, and it can arrive in clear weather where somebody is standing in a dry bed.
WHICH MAKES IT A HAZARD BEFORE IT IS AN OPPORTUNITY. The standing advice in flash-flood country is to treat a dry watercourse as a channel rather than a path, and to know what the weather is doing on the ground upstream rather than overhead.
AFTER IT PASSES, THE FISHING FREQUENTLY IMPROVES SHARPLY, for the reasons above and one more: the pulse reconnects pools that had been separate, which lets fish move for the first time in weeks.
IN A KARST CATCHMENT, RAIN DISAPPEARS. Water falling on limestone goes underground rather than into the channel, so a river can stay clear and steady through rain that would colour a clay-catchment river completely — and can then rise from a spring some distance away with no local rain at all. Slovenia, the Balkan karst and parts of Iberia and Ireland behave this way.
AND ON A TIDELESS COAST, RAIN DOES SOMETHING THE ABOVE DOES NOT COVER. Heavy runoff into an enclosed sea with no tide to mix it produces a persistent low-salinity surface layer that can sit for days over the salt water beneath, rather than being flushed on the next ebb. Fish move under it or away from it, and a mark that fishes well normally can be dead for a week after a storm for reasons an angler cannot see from the surface.
Scientific evidence
Supported by peer-reviewed research or fisheries science. The sources are listed and can be checked.
- Freshwater Fishes of the British Isles — HarperCollins (New Naturalist 75), 1992 (Reference work)Relied on for: Distribution, habitat requirement and life history of European freshwater fishes, including their responses to flow, temperature and salinity.States this directlyCitation checked — the work exists and is described correctly
- The European Environment Agency's assessments of Europe's waters, seas and coasts — European Environment Agency, Copenhagen (Conservation authority)Relied on for: Assessment of Europe's surface waters, including hydromorphological modification, regulation, abstraction and barriers to migration.States this directlyCitation checked — the work exists and is described correctly
- RNLI water safety guidance: cold water shock and Float to Live — Royal National Lifeboat Institution (Water-safety or diver-training authority)Relied on for: Cold water shock and the immersion response, and the water-safety guidance for shore anglers and small-craft users.States this directlyPassage read and verified
Where to go next
Where it matters
What these connections rest on (1)
Practitioner consensus — 1 connection
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
Coarse fishing
Written only where the method's own conduct changes because of the condition — a different rig, depth, retrieve, or a decision to move or stop. Every condition is true of every method, so an edge that merely records that would distinguish nothing.
- Sea Angler — Bauer Media (Specialist angling publication)Relied on for: British sea angling practice: how tide, wind, swell and water clarity change where and how a mark is fished.FishingHQ's interpretation of what it saysCitation checked — the work exists and is described correctly
- Freshwater Fishing — Macdonald & Jane's, 1975 (Specialist angling publication)Relied on for: Comprehensive angling practice across disciplines, including water reading, seasonal condition and the tackle each demands.States this directlyCitation checked — the work exists and is described correctly
Where this applies
What these connections rest on (1)
Scientific evidence — 1 connection
Supported by peer-reviewed research or fisheries science. The sources are listed and can be checked.
Moroccan mountain and reservoir fresh water
A link from a practice, an environment or a geography to the mechanism it rests on. It asserts that the mechanism is load-bearing here rather than merely relevant, which is the test applied throughout this file.
- Freshwater Fishes of the British Isles — HarperCollins (New Naturalist 75), 1992 (Reference work)Relied on for: Ecology, habitat requirement and behaviour of European freshwater fishes in relation to flow, temperature, level and the modification of their waters.States this directlyCitation checked — the work exists and is described correctly
- The European Environment Agency's assessments of Europe's waters, seas and coasts — European Environment Agency, Copenhagen (Conservation authority)Relied on for: Assessment of Europe's surface waters, including regulation, abstraction, hydromorphological modification and the barriers those produce.States this directlyCitation checked — the work exists and is described correctly
Related reading
- Barometric pressure and fishingWhat precedes rain is a set of correlated changes, and attributing the result to the approaching rain specifically means picking one variable out of four that moved together.
- Weather fronts, and what can honestly be saidThe attribution problem is the same one: a front changes pressure, wind, cloud and temperature at once, and no angler is in a position to separate them.
What these connections rest on (2)
Practitioner consensus — 2 connections
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
Barometric pressure and fishing
A mechanism edge joining a situation to the physical or biological reason behind it. Where the underlying mechanism is documented science the object record carries that citation; the association itself is practitioner observation and is labelled as such.
- Angling Times — Bauer Media (Specialist angling publication)Relied on for: Contemporary UK coarse and match angling practice as reported by practitioners, including conditions and seasonal observation.States this directlyCitation checked — the work exists and is described correctly
- Trout & Salmon — Bauer Media (Specialist angling publication)Relied on for: Contemporary game angling practice as reported by practitioners, including river height, water reading and run timing.States this directlyCitation checked — the work exists and is described correctly
Weather fronts, and what can honestly be said
A mechanism edge joining a situation to the physical or biological reason behind it. Where the underlying mechanism is documented science the object record carries that citation; the association itself is practitioner observation and is labelled as such.
- Angling Times — Bauer Media (Specialist angling publication)Relied on for: Contemporary UK coarse and match angling practice as reported by practitioners, including conditions and seasonal observation.States this directlyCitation checked — the work exists and is described correctly
- Trout & Salmon — Bauer Media (Specialist angling publication)Relied on for: Contemporary game angling practice as reported by practitioners, including river height, water reading and run timing.States this directlyCitation checked — the work exists and is described correctly
How this compares
What these connections rest on (1)
Practitioner consensus — 1 connection
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
River levels, and what a flood changes
Two conditions records a reader will weigh against one another, joined where the contrast is what makes either usable.
- Angling Times — Bauer Media (Specialist angling publication)Relied on for: Contemporary UK coarse and match angling practice as reported by practitioners, including conditions and seasonal observation.States this directlyCitation checked — the work exists and is described correctly
- Trout & Salmon — Bauer Media (Specialist angling publication)Relied on for: Contemporary game angling practice as reported by practitioners, including river height, water reading and run timing.States this directlyCitation checked — the work exists and is described correctly
Sources for this page
- Freshwater Fishing — Macdonald & Jane's, 1975 (Specialist angling publication)Relied on for: Comprehensive angling practice including water reading, seasonal behaviour, river conditions and the reasoning behind them.States this directlyCitation checked — the work exists and is described correctly
- Freshwater Fishes of the British Isles — HarperCollins (New Naturalist 75), 1992 (Reference work)Relied on for: Biology, distribution and seasonal behaviour of British and Irish freshwater fishes, including temperature responses and spawning timing.States this directlyCitation checked — the work exists and is described correctly
- Angling Times — Bauer Media (Specialist angling publication)Relied on for: Contemporary UK coarse and match angling practice as reported by practitioners, including conditions and seasonal observation.States this directlyCitation checked — the work exists and is described correctly
How FishingHQ labels evidence is explained in the evidence policy.