Reading a wind on a big lough

Ask anyone who has fished the big western loughs what they want from a day and they will mention the wind before they mention the flies.

There is a reason for that, and it is worth understanding rather than just repeating.

Why flat calm is hard

A dead calm looks lovely and fishes badly, most of the time.

Two things are going on. The surface becomes a mirror, so a trout looking up sees everything above it clearly, including your leader, your line and you. And there is no wave action to disturb the surface film or move food around, so the fish have no reason to come up and every reason to stay deep and cautious.

A good ripple fixes both. It breaks up the window the fish is looking through, it puts movement into the surface, and it starts moving food. You do not need much. A wave you would describe as a decent ripple is usually better than a flat calm and better than a big lump of a sea.

Too much wind is its own problem, mostly a boat handling one. When you are spending more attention on staying safe and holding a drift than on fishing, the fishing suffers whatever the trout think about it.

Where the wind puts the food

This is the part worth actually knowing.

Wind pushes surface water across the lough. That water piles up on the downwind shore and has to go somewhere, so it sinks and returns along the bottom. Everything floating on the surface, spent flies, terrestrials blown off the land, hatching insects, gets carried the same way.

So the downwind shore accumulates food. It is often coloured, often has a bit of chop against it, and it frequently holds fish that are there because the dinner arrives.

The upwind shore is usually clearer and calmer, and often thinner fishing.

There are exceptions and every water has its own. A shore that always fishes well in a westerly regardless of the theory is a fact about that lough and you should trust it over the general rule.

Wind lanes

On a decent breeze you will often see smooth stripes running down the lough between the rougher water. Those are wind lanes, and they are where the surface film concentrates.

Food gathers in them. Fish know it. A trout working steadily up a wind lane in the evening is one of the more reliable sights in Irish lough fishing, and a fly presented properly along the lane will often get an answer when the same fly twenty yards away gets nothing.

If you see a lane, fish it before you fish anything else.

Picking a drift

The traditional way is to set up so the boat drifts with the wind, covering new water continuously, with the anglers casting ahead of the drift.

A few things that matter more than they look:

Fish the water that is coming to you, not the water you are passing. Casting behind the drift covers water the boat has already disturbed.

Start the drift well upwind of where you think the fish are. Boats push fish. By the time you reach the good water on a short drift you have already announced yourself.

Use a drogue when it is windy. It slows the drift enough to actually fish the water rather than skate over it, and it makes boat handling far safer.

Long drifts beat short ones. Repeatedly motoring back up disturbs more water than most anglers realise.

A shifting wind

A wind that swings during the day changes where the food is, and the fish follow it, though not immediately. There is usually a lag of an hour or more.

The practical version: if the wind has been in the west all morning and swings to the south at lunchtime, the western shore is probably still the better bet for a while. Do not chase the change too quickly.

What actually matters more

Wind is the one anglers talk about, but it is not the only thing.

Water temperature decides how deep and how active fish are. Light and cloud change what they will look at. Recent rain changes the colour of the water and, on a river-fed lough, changes everything. Pressure gets discussed a great deal and the evidence for it is thinner than the conversation suggests.

The honest summary is that conditions shift the odds. They do not fill a boat. Someone who reads the water well will out-fish someone who reads the forecast well, most days.

Safety

Big Irish loughs are more dangerous than they look, and they catch out people who mostly fish rivers. Wind against a large fetch builds a serious wave surprisingly quickly, and squalls arrive with very little warning.

Lifejackets on, tell someone where you are going and when you will be back, watch the forecast for the change rather than the current reading, and do not be embarrassed about coming in early. Nobody has ever regretted that.

Lough Logic pulls together the weather and water conditions for 24 Irish waters and suggests what that means for how to fish them. Free, no account needed.

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