How the weather affects fishing...

There’s no doubt that fundamental elements such as wind, rain, the sun and perhaps even the phases of the moon affect our sport. But how much?

“Bites do seem to dry up when the heavens open”

WE CERTAINLY know a lot about the weather in the UK – from reports on TV to phone apps we are bombarded with information of varying quality on a daily, sometimes hourly, basis. But does the weather really have as much impact on fishing as we think? And if it does what are the best conditions to look out for?

Light levels

Cloudy, overcast days often produce great sport in the same way that fishing early in the morning or late in the evening can be good. Low light levels very often coincide with a spike in feeding behaviour in many species. Invertebrates, the main food of most coarse fish, tend to hate light and so come to the surface of the lake or riverbed when the light levels are lowest, making them easier to catch. Predatory fish also find it much easier to catch their prey unawares when the light levels are low. These fish often have large eyes and are well camouflaged, enabling them to stalk prey fish much more closely. The difference between a sunny and a cloudy day can be enough to tip the advantage in their favour.

Rain

Why should it be that fish feed less when it is raining, if in fact they do? Well, the circumstantial evidence is very strong, as bites do often seem to dry up when the heavens open. This is especially true for predatory fish, such as pike, which rely upon their lateral line system in part to hunt. The drumming of rain drops on the surface will interrupt the finely-tuned lateral line and make it difficult for the fish to hunt effectively. Rain does not have the same chemical composition or temperature as lake or river water, and so a heavy shower can affect the water’s chemistry. Rain can have a cooling effect and a temperature drop of only a tenth of one degree can stop fish from feeding. Rain is also likely to be more acidic and carries less oxygen than the lake or river water, so can again have an adverse effect on the feeding behaviour of fish.

Wind

The wind can have several effects, some not always obvious, on our catches. Ripple on the surface caused by the wind can reduce the light levels

below quite significantly. This is especially true if the waves are at an angle to the sun. If, however, the waves are rolling directly towards the sun the light level may actually increase because more of the suns rays will be able to penetrate below the surface. Within a few minutes of a breeze picking up the oxygen level in the surface layers will start to increase as the increased surface area and broken boundary layer enables more oxygen to be absorbed and more carbon dioxide to be released from the water. Oxygen levels can be depleted, in particular during the summer months leading to reduced feeding in fish, so the onset of a breeze can very quickly prompt fish to start feeding. A strong wind whipping across a large lake can cause a lot of water movement and disturb the sediment on the bottom and cause weedbeds to move around. Both of these factors can also affect the fish. Fish will often feed more confidently in coloured water, so as the windward bank becomes more murky the fish will often feed in earnest. Species that like to inhabit weedbeds, such as pike and rudd, can be disturbed by movement caused by the wind and may leave this sanctuary and move into open water when the wind is strong, making them more catchable. Whether the wind warms or cools the water depends on the relative temperatures of the water and the air. Generally speaking, a warm wind from the South or West is likely to be hotter than the water. Over a few hours this will mean that the windward shore will become slightly warmer than the rest of the lake. The converse if often true if the wind comes from the East or North and these cold winds can cool the water.

Moon phase

The phase of the moon is one of those factors that some anglers set great store in while others dismiss it completely. The truth probably lies somewhere in between

“Species that like weedbeds can be disturbed by movement caused by wind”

because there is increasing evidence that many animals react to the moon phase, especially those in the sea. This makes sense as the moon creates tides which have a direct influence on marine animals. But what about in freshwater? One theory is that the moon phase acts as an astronomical clock, triggering creatures to migrate, spawn, or feed in unison irrespective of the weather. Doing something in numbers is a great way of avoiding predation. Of course, knowing that there is going to be a light South Westerly wind with dry but overcast conditions and a good moon phase next Thursday is all very well if we can actually go fishing that day. The chances are that by the weekend the conditions won’t be anything like as conducive. But, just knowing if the weather is improving or not can give us a clue about how the fish are likely to react.