Skip to content
EN
PT PortuguêsES EspañolEN English
weather and moon · beginner · 4 min

how weather affects fish

Pressure, cold fronts, friagem (cold spells), wind, rain and water temperature: what changes in fish behavior, and how to read the app's index, confidence and forecast horizon.

atmospheric pressure

Steady or slowly falling pressure is usually good. The drop before a front can bring a spike in activity. A sharp rise after the front, with clear skies, usually shuts fishing down.

A front changes pressure by roughly 5 to 15 hPa, and 1 hPa is about 1 cm of water column. Fish sense more pressure change dropping half a meter than with a whole front. So pressure works more as a signal of the whole package (light, wind, temperature) than as an isolated cause.

tips

  • Look at the trend, not the number: rising, steady or falling.

cold front and friagem

A cold front is the arrival of a cold air mass. In the South and Southeast it's common in autumn and winter. In the Center-West and Amazon, the strongest ones turn into friagem.

tips

  • Before: muggy heat, north or northwest wind, falling pressure and building clouds. Usually a good time to fish.
  • During the passage: the wind shifts to south or southwest, with rain, gusts and a drop in temperature. Get out of the water if there's lightning or strong wind.
  • After: clear skies, cold air, south or southeast wind and high pressure. These are the hardest days; fish sit still, deeper or hidden away in some cover.
  • Recovery: with stable weather and warming water, activity returns in 2 to 3 days.
  • Friagem: in the Amazon and the Pantanal, temperature can drop more than 10 °C in a few hours. Peacock bass are very sensitive and stop striking for 1 to 3 days. Prefer slow lures, mid-water and bottom, and the warmest hours.

wind and rain

Wind and rain change light, oxygen, water color and safety. Adjust your spot and your lure.

tips

  • Light to moderate wind ripples the water, cuts the light, oxygenates it and pushes plankton and food toward the shore that takes the wind. Fish the windward shore.
  • Strong wind spoils casting, makes it hard to feel the lure and kicks up dangerous waves. On a big reservoir, the waves build fast.
  • Light rain and overcast skies are usually good: less light and more willing fish.
  • Heavy rain muddies the river. In murky water, use lures with vibration and noise in dark or bright colors, or look for cleaner water in tributaries and river mouths.
  • Lightning: stop fishing and get out of the water.

water temperature

Fish take on the temperature of their surroundings. Each species has an ideal range and, outside it, feeds less. A sudden drop of 2 to 3 °C already makes a difference.

tips

  • Measure the surface temperature (your sonar usually shows it) and compare it with the species' ideal range in the app.
  • In winter, fish the warmest hours, the banks that get afternoon sun and shallow water, which warms up fast.
  • In strong summer heat, prefer dawn, dusk and deeper or shaded water.
  • Cold water calls for a smaller, slower lure with long pauses.

how to read the app's forecast

The fishing forecast combines the predicted weather with the moon, the tide and what's known about each species. Three things matter: index, confidence and horizon.

tips

  • Index: a score of how favorable the conditions are for the chosen species and spot. It's for comparing days and times, not a promise of fish.
  • Confidence: how firm the forecast is. It drops when the weather models disagree and the further away the date is.
  • 1-day horizon: hour-by-hour detail and high confidence. Use it to pick when to leave.
  • 7-day horizon: the weather is still reasonably predictable, especially in the first 5 days. Use it to pick the day.
  • 14-day horizon: shows trends, such as an approaching front or warming water. Medium to low confidence. Use it to pre-select windows.
  • 28-day horizon: the weather becomes almost just the seasonal statistics. What stays firm is the moon, the tide and the species' season, which are calculated. Use it to plan a trip, never to cancel because of rain.
  • Check again as the date gets closer: the 28-day forecast becomes a 14-day one, then a 7-day one, and gets more accurate.

common mistakes

  • Treating the 28-day index as a certainty.
  • Ignoring confidence and looking only at the score.

checklist

Check off what's ready. Saved on this device.

sources and references

  1. scientific Stoner, A. W. (2004). Effects of environmental variables on fish feeding ecology: implications for the performance of baited fishing gear and stock assessment. Journal of Fish Biology 65(6): 1445–1471.
  2. scientific Kuparinen, A.; Klefoth, T.; Arlinghaus, R. (2010). Abiotic and fishing-related correlates of angling catch rates in pike (Esox lucius). Fisheries Research 105(2): 111–117.Links weather conditions and moon phase to the catch rate of pike, a temperate-climate species. Metadata checked on Crossref; the original abstract is paywalled, so we checked only the automatic abstract from Semantic Scholar.
  3. scientific Heupel, M. R.; Simpfendorfer, C. A.; Hueter, R. E. (2003). Running before the storm: blacktip sharks respond to falling barometric pressure associated with Tropical Storm Gabrielle. Journal of Fish Biology 63(5): 1357–1363.

keep reading

weather and moon

tides and moon in fishing

Spring and neap tides, high and low tide, slack water, rising and falling tide, tide tables and solunar theory: what really matters and how to use it without fanaticism.

boating and travel

planning a fishing trip

How to choose the season and destination, get licenses, choose between a live-aboard boat and a lodge, bring your rods, pack, and use the app's 14 to 28-day forecast to pick your dates.

safety

water safety

Life vest, navigation plan, lightning, wind and waves, hypothermia, dehydration, first-aid kit and the paperwork the Navy requires.