Why an overcast day is best for predatory fish

For a long time I thought the best fishing days were when the sun was shining and the sky was clear. I set out on days like that a few times with high hopes and came home with an empty bucket. Then one autumn afternoon at Rėkyva, when the sky was grey as tin and I was already getting ready to head home, the pike started biting one after another. Since that day, an overcast day isn't a reason for me to stay home – on the contrary, it's a sign to get ready for serious predatory-fish fishing.

Why this happens

The explanation is fairly simple once you think about how a pike, perch or catfish actually sees the world. Their eyes are built for low light – lots of light-sensitive cells, a wide pupil. On a clear day, when the sun beats down mercilessly, it's simply too much light for them, and they rest in the shade, under vegetation or deeper, out of the way. When clouds cover the sky, everything changes – they feel safer and swim out into open water to hunt more boldly.

There's another side to it too – when there's less light, smaller fish also behave more boldly and rise closer to the surface. And wherever the small fish are, the ones that hunt them soon follow.

Not every cloudy day is the same

Over time I noticed that not all overcast days give the same result. When the sky is only barely covered – maybe 20-30 percent – fish are still fairly cautious, activity is only a little better than on a clear day. It really gets going somewhere around the 60 percent mark and above – that's when I start seeing a difference at the water. And a fully overcast day, especially combined with a light drizzle, is usually the best of all.

By the way, about rain – if you're already out and it starts to drizzle, don't run for the car. Drops hitting the water create small vibrations that draw small fish toward the surface, and predators sense it immediately. I remember more than once when the bite started exactly as the rain began – as if someone flipped a switch. Rain also oxygenates the water, especially after a long hot spell – which is another benefit for the fish.

How different fish behave

When it's overcast, pike become a different fish entirely – more active, bolder, often swimming out into open water rather than just holding at the edge of vegetation as usual. On a cloudy day, perch gather in larger shoals and chase bait more actively – if you see them jumping at the surface, that's a good sign it's worth fishing near that shoal. And catfish, which normally only hunt at night, sometimes decide to have an early lunch on an overcast day – you can get bites even at midday, which would be almost unthinkable on a clear day.

And if the day is clear after all

Of course, you can't always choose the weather – sometimes a free day happens to fall exactly when there isn't a single cloud in the sky. In that case I fish early in the morning or late in the evening, while the sun is still low, and choose spots with shade – under a tree, a bridge, among plants. I choose more natural, muted-coloured lures, and fish deeper, where the light doesn't penetrate as strongly.