How the KLEWA Bite Index Works

The KLEWA bite index is a 0–100 score of relative fish feeding activity, computed hourly as capacity × opportunity × post-front penalty. It is an evidence-based activity index — not a promise of a catch — and every factor in it has to earn its place with published research.

What the index is — and what it is not

The index answers one question: compared with other hours at this spot, how favorable is this hour for the species you picked? A score of 80–100 means excellent conditions, 60–79 good, 40–59 fair, and 0–39 poor.

It is not a calibrated probability of catching fish. Factor weights are an evidence-informed expert decision, and we say so openly; they will become data-calibrated once enough real catch logs are collected. What the index will never include is folklore: if a factor has no reproducible evidence behind it, it stays out — no matter how popular it is.

Step 1 — Capacity: can the fish physically feed?

Fish are ectotherms: their metabolism is set by water temperature. The capacity gate multiplies three biophysical terms:

Thermal gate — every species has a temperature range where it can digest food; outside it, appetite collapses. This is why a trout forecast at 28 °C water scores ~6, not ~96 as naive models suggest.
Dissolved oxygen — computed from real solubility physics (the APHA / Benson–Krause relationship), corrected by barometric pressure (× P/1013.25) and wind re-aeration. This is the only role air pressure plays in the model: it changes oxygen, not fish "mood".
Temperature trend — species-specific triggers such as the pre-winter feeding surge on an autumn cooldown, or accelerated feeding on a spring warm-up.

Step 2 — Opportunity: how favorable is the moment?

When the fish can feed, a weighted blend of moment factors scores how likely it is to feed now. The weights sum to 1.0 and follow the strength of the evidence:

Light / time of day — 0.32. The dominant intraday driver, computed as a continuous curve from real sunrise and sunset times.
Cloud cover — 0.20. Light and water clarity effects, species-specific in sign.
Wind speed — 0.15. Aeration and baitfish drift; wind direction is excluded (no evidence).
Pressure trend — 0.15. A proxy for weather fronts — the trend matters, not the absolute number.
Precipitation — 0.12.
Season / spawning — 0.06. A species prior.

Step 3 — The post-front penalty

The classic "bluebird sky" stupor: after a front passes, clear sky combined with rising pressure suppresses feeding for 24–48 hours. The index applies a multiplier from 0.82 (clear and rising) to 1.0 — catching the weather pattern itself rather than superstition about pressure.

What we deliberately exclude — and why

Three staples of fishing folklore are absent from the index because controlled studies fail to support them:

Moon phase. Solunar theory does not reproducibly predict freshwater feeding activity, so full moon and new moon score the same.
An absolute pressure "optimum". Absolute pressure mostly encodes altitude; a lake at 964 hPa is not worse than one at 1014 hPa. Pressure only enters through oxygen solubility and the trend.
Wind direction. "East wind — no fish" does not survive testing; only wind speed carries signal.

From hourly scores to your forecast

The daily index takes the best 8 hours of the day and combines them robustly: 60% median + 40% mean. Golden windows are the contiguous runs of top-scoring hours (the inconvenient 01:00–03:00 night window is skipped).

Weather comes from OpenWeatherMap; water temperature and pressure history come from Open-Meteo; day/night boundaries use astronomical sunrise and sunset for your exact coordinates. Species behavior is configured separately for all 12 supported species, with seasonal profiles per species.