How the ReelConditions fishability score works

Every number on this site comes from five measurable inputs and one honest admission: fish do not read forecasts.

The algorithm, explained without hand-waving

Most fishing forecast sites hand you a number and never tell you where it came from. That is a reasonable way to protect a proprietary model and a poor way to help someone decide whether to get up at four in the morning. So here is the whole thing.

ReelConditions scores every hour of the next seven days from 1 to 99. Each hour gets five sub-scores, each sub-score is normalised to a 0–1 range, and they are combined with weights that depend on the species you selected. Penalties for genuinely bad conditions — heavy rain, freezing air, dangerous seas — are applied at the end as a multiplier.

1. Barometric pressure and its trend

This is the input anglers argue about most and the one with the most consistent experiential support behind it. What matters is not the absolute reading so much as which direction it is moving and how fast.

ReelConditions compares the current sea-level pressure to the reading three hours earlier and buckets the change:

That bucket is then multiplied by an absolute-level factor. Very high pressure (above 1025 hPa) knocks it down to 72% of its value; the comfortable 1005–1020 hPa band passes through untouched; a very low reading below 998 hPa pulls it down again, because at that point you are usually looking at weather that keeps you off the water entirely.

The physical mechanism is still debated. The most credible explanation is that pressure change affects the swim bladder, which affects a fish's sense of its own buoyancy and depth, which affects how willing it is to move through the water column. Whatever the cause, the pattern shows up in enough catch records to be worth weighting heavily.

2. Tide movement

For saltwater, this is frequently the single most important factor, and ReelConditions treats it that way — up to 42% of the total weight for species like fluke.

Crucially, the score is driven by rate of change, not tide height. A six-foot high tide sitting motionless at the top is worth far less than a three-foot tide ripping through the middle of its cycle. Moving water disorients bait, concentrates it against structure, and tells predators where to sit.

NOAA publishes high and low times for about 3,500 US stations. ReelConditions finds the stations nearest your coordinates and uses the closest one that actually returns predictions. How far it will reach depends on whether the marine model has data for your point: if it does, you are on or near the ocean and a gauge up to 87 miles away is accepted, because a back-bay spot can sit a long way from its reference station. Genuinely inland points get a tight 34-mile radius, and beyond that the location is treated as freshwater. It then reconstructs a smooth curve between each successive high and low with a cosine interpolation:

h(t) = (h₁+h₂)/2 + (h₁−h₂)/2 · cos(π · (t−t₁)/(t₂−t₁))

This is mathematically the same shape as the old rule of twelfths that mariners have used for a century, and it has one large practical advantage: it works at every NOAA station, including the subordinate stations that only publish high and low times rather than a full harmonic series. The derivative of that curve gives flow rate in feet per hour, which is then normalised against the strongest flow that station sees during the week. Slack water floors at 0.20; peak flow reaches 1.00.

3. Wind

Wind does three separate things and the score tries to respect all of them. A light chop breaks up surface light and gives fish confidence to move shallow. Moderate wind stacks bait on a lee shore. Too much wind makes fishing unpleasant, then unsafe.

Each species has a preferred wind band — 6–20 mph for striped bass, 2–11 mph for trout, 0–12 mph for blackfish at anchor. Inside that band the sub-score is 1.00. Outside it, the score falls off linearly, reaching zero roughly 13 mph past the upper bound. Two further adjustments apply:

• Dead calm penalty. Below 1.5 mph the score is cut to 80%. Glass-calm water makes fish spooky and shuts down surface mixing.
• Gust penalty. Gusts above 28 mph cut the score to 62%; above 38 mph, lower still. A 15 mph average with 40 mph gusts is not a 15 mph day.
• Direction. A gentle ±7% adjustment favouring west and southwest over east and northeast. This is the old rhyme — wind from the west, fish bite best; wind from the east, fish bite least — and it is deliberately weighted lightly, because most of its real predictive power is just a proxy for the pressure trend already counted above.

4. Moon and solunar periods

ReelConditions computes the moon's position astronomically for your exact latitude and longitude rather than looking anything up in a table. From that it derives the four solunar periods that John Alden Knight described in the 1930s:

• Major periods — when the moon is directly overhead (transit) and directly underfoot on the opposite side of the earth. Roughly 2.5 hours wide, centred on the event.
• Minor periods — moonrise and moonset. Roughly 1.5 hours wide.

An hour inside a major period scores up to 1.00, a minor up to 0.78, and everything else sits at a 0.34 baseline. That result is then modulated by up to 16% based on proximity to a new or full moon, when tidal range is greatest and the effect compounds with factor 2.

Be honest with yourself about this one: solunar theory has enthusiastic support and thin controlled evidence. It is weighted at 12–22% depending on species — enough to break a tie between two otherwise identical afternoons, not enough to override a collapsing barometer.

5. Light

Sunrise and sunset times come from the weather model for your coordinates. The hour and a quarter either side of each gets the top light score. Full night sits at 0.55. Daylight hours scale from 0.42 to 0.77 based on cloud cover, because overcast midday genuinely does beat bright midday for most species.

Then the species multiplier applies. Walleye multiply low-light hours by 1.70. Catfish by 1.60. Weakfish by 1.45. Flats species invert the logic entirely — for bonefish and permit the score peaks at solar noon under a clear sky, because you cannot sight-fish what you cannot see.

Penalties

Applied last, as multipliers on the combined score:

• More than 0.30 in of rain in the hour: ×0.72
• Air temperature below 20 °F: ×0.72  ·  below 32 °F: ×0.88  ·  above 98 °F: ×0.80
• Seas over 6 ft: ×0.70  ·  over 9 ft: lower again

How the daily rating is built

The number on each of the seven day cards is not a simple average. It is 0.65 × (best 4-hour window) + 0.35 × (daily average). A day with one outstanding dawn and eleven mediocre hours deserves to beat a day that is uniformly average, because you are going to fish the dawn.

What the score cannot know

A short and important list:

• Water temperature at depth, and therefore whether fish have moved or turned over. Sea-surface temperature is shown where available; lake temperatures are not modelled at all.
• Water clarity. Three days after a heavy rain, a productive river can be unfishable chocolate milk with a perfect barometer above it.
• Whether the fish are there. Migration timing, bait presence, spawning stage and fishing pressure all swamp the weather on any given day.
• Your skill and your spot. A good angler on a 40 day will out-fish a beginner on an 85.

Use the score the way you would use a surf report: to choose between days, to pick which end of the day to fish, and to know when to stay home and re-spool. Not as a promise.