About Best Days to Fish

A grade weighs the conditions below, adjusted for the species you pick, and also accounts for the quality and duration of available fishing windows. A strong short session can still have a lower daily grade than a similarly strong day with more flexibility. The weights are informed by published fisheries research.

Stoner (2004) in Journal of Fish Biology found water temperature, light, current and prey able to move catch rates by an order of magnitude.

Shaw, Renik & Sass (2021) in PLOS ONE, a 12-year creel study at Escanaba Lake, measured how weather, light and the moon affected walleye and muskellunge catches species by species.

Quigley et al. (2023) in SN Applied Sciences, 361 trout trips by one angler in Utah, found no significant link between solunar tables and catch rates, while air temperature did predict them.

• Water temperature. The largest weight: 23% on fresh water and 22% on the coast.
• Wind. Its speed and how steady it is. Direction is not scored for its own sake: a review by Lennox and colleagues (2017) traced the apparent effect of wind direction to the weather systems that bring it. A northwesterly does count as one sign that a cold front has passed. Wind barely changes a bite, but a sustained 20 mph and up, or thunder, makes an hour unsafe to be out in, and the day's grade is held down by how much of its daylight those hours fill.
• Tides or river flow. How much the water is moving, and which way it is heading.
• Rain, cloud and sun. Recent rainfall, and how much light reaches the water.
• Air temperature and humidity. Air temperature was the one condition that predicted trout catch rates in the Utah study.
• Pressure. Scored on its level and on how fast it is changing, which is how a front shows up, at 7% on fresh water. Two whole-lake studies of pike (Kuparinen, Klefoth & Arlinghaus 2010; Arlinghaus et al. 2017, both in Fisheries Research) found no direct effect of pressure on catch rates, so it carries less than most apps give it. The wind, sky and temperature change that come with a front still count, each in its own factor.
• The moon. Moon phase and the moon's distance carry 4% of a day's grade. The solunar feeding periods, from John Alden Knight's 1926 tables that many apps are built on, shape the hour-by-hour chart and the best hours. Those hours also inform the daily opportunity limit.

Coastal and freshwater spots use different factors, and the weights shift with the season. When you pick a species, its own temperature range, spawn timing and feeding hours adjust the result, and a day whose water is outside what that fish can stand is capped however good the weather looks. With none picked, the hours follow a typical fish's day, busiest at dawn and dusk. Every factor and its weight are on each forecast card, and how we score sets out the whole method.

A grade says when conditions favor feeding. It is not a promise of fish, and where no gauge measures your water, the forecast says the figure is modeled rather than pretending it was measured.