Temperature and fishing: why warmth drives everything

In spring, the shallows warm first, so look at shallow bays, margins and the sunny north bank (which faces south). In high summer, look for oxygenated water: the windward end, deeper water and shade. In winter, fish often hold in the deepest or most stable water, or in the warmest shallow on a sunny afternoon.

In cold weather pick a peg where you can reach deeper water or known winter holding spots. In spring, a peg overlooking a shallow bay that catches the sun can be gold. In summer heat, a peg with shade and a breeze is kinder to you and the fish.

Warm water: fish are hungry, so particles, pellets and bigger beds of boilies come into play. Cold water: fish need little food, so scale right down — single hookbaits, small bright pop-ups, maggots and a few freebies.

When it's above the mid-twenties, oxygen levels drop and fish stress more easily. Keep fish in the water as much as possible, use a wet mat, skip the long photo session and don't retain fish. Many venues have rules about this in hot spells.

On a sunny spring afternoon the air might hit 18°C while a big gravel pit is still sat at 9°C. That's why fish don't always respond to a warm day as quickly as anglers hope. A cheap thermometer on a string, dropped in your margin or out over your spot, tells you far more than a phone forecast.

Shallow lakes and margins heat and cool fast; deeper water stays more stable. So on a cold morning the deep water may be the warmest place in the lake, while by afternoon the shallows can overtake it.

A rising temperature is usually the green light. Even a couple of degrees over a few days in spring can see fish move into the shallows and start feeding. A sudden drop, especially after a warm spell, often shuts things down for a day or two while fish adjust. Steady temperatures, warm or cold, let fish settle into a routine you can learn.

Below about 8°C, think small: single hookbaits, short sessions, fishing the warmest part of the day and moving to fish rather than waiting. Between about 10–15°C, fish begin to respond to more bait, and PVA bags and small beds work well. From the mid-teens to the low twenties, it's prime time — particles, pellets, spods and method feeders come into their own. Above the mid-twenties, early mornings, late evenings, surface baits and zigs are often the way to go.

In deep lakes during a long hot spell, the water can split into a warm top layer and a cold, low-oxygen bottom layer. Fish often avoid the deep stuff, which is why a bait in 25 ft of water in August can go untouched. Fish shallower or up in the water instead.

Piling bait in when the water is cold — it simply sits there. Fishing the same deep winter spot into May when fish have already moved to the shallows. And trusting air temperature alone, especially after clear, frosty nights.

Every lake behaves differently. Small, shallow club ponds warm up in a few sunny days and cool just as fast. Big, deep gravel pits can take weeks to warm in spring and stay mild long into autumn. Rivers vary again, with flow and rain having a huge say. Keep a simple log of water temperature and results on the waters you fish most and you'll soon see patterns that no forecast can give you.