WX Score Explained
How the WX Score is calculated, what factors affect it, and how to interpret your number.
What Is the WX Score?
The WX Score is a 0–100% rating of how well the forecast weather conditions match your specific aircraft capabilities and personal minimums. It starts at 100% (perfect conditions) and points are deducted for each weather factor that approaches or exceeds your limits.
Important: The WX Score is an advisory tool, not a flight authorization. Two pilots with different experience levels and aircraft will get different scores for the same flight because their personal minimums differ. The PIC always makes the final fly / don't-fly decision.
Why the Score Carries Weight
The WX Score isn't PlaneWX's opinion of what's safe to fly. It's your own personal minimums, applied consistently, every time. That's why they're required: PlaneWX can't generate a score without them. No one wants to launch on a low number, and that's the point. A low score doesn't mean don't fly. It means don't fly without asking why the number is what it is.
Favorable (75 and up)
Conditions are within your minimums. Normal flight planning applies.
Marginal
Some conditions are close to or slightly exceed your limits. Review the briefing carefully.
Unfavorable
Deductions bring the score under 50, or a hard limit is exceeded, which sets it to 0%. See What 0% Means below. This is not the same as “mission impossible.”
What 0% Does (and Doesn't) Mean
A 0% WX Score does not mean the flight is impossible. It is not a command to stay on the ground.
In plain terms: 0% means unlikely as planned — not “you have no chance of making this flight.”
The score evaluates this specific flight plan — your route, cruise altitude, and departure time — against your personal minimums and aircraft capabilities. It models conditions along that planned path. When the score hits 0%, at least one factor exceeds a hard limit you set, or the cumulative deductions bring the score to zero.
What 0% is telling you
- • Forecast conditions, as modeled on your current plan, exceed one or more of your hard limits
- • The nominal route and altitude may require more weather exposure than your minimums allow
- • You should read the Score Breakdown to see exactly which factors triggered the result
What 0% is not accounting for (yet)
In real flying, you routinely adapt. You might delay departure, climb or descend to escape icing or turbulence, deviate laterally around buildups, or stay VFR clear of clouds. You might accept a high-workload flight and complete it without diverting. PlaneWX is evolving toward scoring those pilot options more explicitly. Today, the WX Score still leans conservative: it scores the plan as written more than the flexibility you bring in the cockpit.
Experienced pilots sometimes fly successfully on days that score 0% — because they actively manage the weather, not because the forecast was wrong. A low score means the default plan doesn't fit your limits well. You decide whether your experience, aircraft, and willingness to adjust make the trip reasonable.
If you're instrument-rated and the airplane is IFR-certified, a VFR 0% driven by ceilings or visibility may not be the whole story. PlaneWX can show the WX Score under IFR on the same weather — see Switch to IFR.
Bottom line: Treat 0% as “conditions don't support this plan under your stated limits” — then use the briefing, your alternatives, and your judgment as PIC. PlaneWX supports your decision; it doesn't make it for you.
How Points Are Deducted
The score starts at 100% and deductions are applied for each weather factor that doesn't meet your minimums. The size of each deduction depends on how far conditions exceed your limits.
Ceiling & Visibility Deductions
Points deducted when forecast ceilings or visibility fall below your personal minimums at departure or arrival. If you haven’t saved personal minimums, VFR trips use a 3,000 ft ceiling and 5 SM visibility at departure and arrival. IFR trips use 500 ft and 3 SM. Your saved minimums always win. If you have set airport-specific limits for the departure or destination airport, those apply instead of your global limits at that airport. For VFR flights, en-route wildfire smoke visibility is scored the same way against your VFR visibility soft/hard minimums (see Wildfire Smoke). IFR flights show smoke for awareness only. It does not deduct from the score by itself.
Near departure, a fresh METAR (observation within about 90 minutes of your time at that airport) can drive ceiling and visibility. If the METAR is older than that, or if the station is not reporting live, PlaneWX uses the covering TAF or a nearby proxy station instead, and notes that on the briefing. A leftover cached SPECI from an out-of-service station is not scored as current conditions.
- • Soft limit exceeded: 5–15 points (marginal conditions)
- • Hard limit exceeded: 100 points (automatic 0%)
Crosswind Deductions
Based on the crosswind component on the best aligned runway that meets your aircraft's minimum runway length at departure and arrival. The deduction scales with your pilot certificate and total hours:
- • Student/Sport/Recreational: Stricter crosswind limits
- • Private (<500 hrs): Standard crosswind limits
- • Private (≥500 hrs) / Commercial / ATP: Higher crosswind tolerance
Wind Gust Deductions
Separate deductions for wind gusts that exceed your maximum crosswind gust limit. Heavy gusts at departure or arrival can significantly reduce the score.
Turbulence & Icing Deductions
Based on multi-model analysis of turbulence severity at your cruise altitude and icing conditions relative to the freezing level (models chosen by route geography). Moderate or severe conditions reduce the WX Score. The Summary Overall word is then aligned to the resulting score band (Favorable, Marginal, or Unfavorable) unless the Summary gives a more cautious word with a reason.
Convective & Thunderstorm Scoring
Thunderstorm and convective activity penalties use a horizon-scaled approach. A thunderstorm forecast 36 hours out does not carry the same weight as one 3 hours out, because convective forecasts become much more accurate as departure approaches.
Horizon Scaling
The penalty for convective activity is multiplied by a factor that increases as departure approaches:
36+ hours
~40%
of full penalty
12–24 hours
~60%
of full penalty
6–12 hours
~80%
of full penalty
0–6 hours
100%
full penalty
Threat Level Refinement
The base convective penalty is further refined by the threat level from model data and WPC (Weather Prediction Center) analysis:
- • Isolated: Lower multiplier — small penalty for scattered pop-up cells
- • Scattered: Medium multiplier — moderate penalty for organized convection
- • Widespread: Full multiplier — significant penalty for large-area activity
Why horizon scaling matters: Horizon scaling gives distant TAF thunderstorm probabilities (such as a PROB30 group) a smaller impact than near-term ones, so your score tracks risk nearer to departure rather than swinging hard on far-out convective updates.
Convective SIGMETs & Product Dedup
Near-term Convective SIGMETs are scored with time-aware encounter logic: storm motion, your track, tops, and how hard a lateral deviation looks. A SIGMET that only sits in the search corridor while you fly away from it is not treated like a head-on encounter.
The server also keeps a convective ledger so the same storm is not fully stacked as both a SIGMET line and a TAF thunderstorm group. Distinct events still deduct separately. Full walkthrough: Convective Watch scoring.
Pre-Flight Check (Within 12 Hours)
For flights departing within 12 hours, PlaneWX runs a detailed server-side pre-flight check that evaluates every weather parameter against your personal minimums and aircraft capabilities. If any hard limit is exceeded, the score is automatically set to 0%.
What the Pre-Flight Check Evaluates
- •Ceiling and visibility at departure and arrival vs. your soft/hard minimums
- •Crosswind and gust components on the best available runway
- •PROB30 TAF periods (PROB40 on US military and some international TAFs) for thunderstorms, freezing rain, and low visibility
- •TEMPO periods with significant weather (TS, FZRA, SN)
- •Active SIGMETs and Convective SIGMETs you are expected to encounter (time-aware; corridor-only / flying-away polygons are scaled, not auto-stacked with the same TAF TS)
For flights more than 12 hours out: The score is calculated using AI-generated weather analysis and model data, without the detailed pre-flight check. As your flight approaches, the briefing will automatically refresh and the pre-flight check will activate, potentially changing the score.
Score Breakdown
Tap the WX Score ring or the “Score Breakdown” button to see exactly which factors contributed to your score. Each deduction shows:
- • Category: Which weather factor (ceiling, wind, turbulence, etc.)
- • Points: How many points were deducted
- • Reason: A plain-English explanation of why
- • Location: Whether it applies to departure, arrival, or en-route
Tip: If you disagree with a deduction, check your Personal Minimums and Aircraft Profile settings. The score is based entirely on your configured limits. Adjusting them will change your score.
For trips more than 12 hours out and up to 72 hours out, the WX Score leans on airport forecast guidance in this order: TAF, then MOS (MAV or MEX), then NBM, then model data.
When a run is too old
MOS bulletins count as old after 12 hours (MAV) or 24 hours (MEX). PlaneWX compares the model run on the bulletin to when your briefing was built. If that age cannot be read or the run time looks wrong, the bulletin is treated as old.
When the bulletin is old, the score breakdown can show a line like: Forecast guidance at KASH is from a run about 29 hours old. That line is worth zero points. It explains what happened; it does not deduct from the WX Score. If the age cannot be read, you may see: Forecast guidance at KASH is from a run whose age could not be verified.
What that does to the WX Score
When the guidance run is old at either airport, PlaneWX scores the trip's ceiling and visibility with model data ahead of MOS and skips the MOS gap checks. The result can be higher or lower than it would be with fresh guidance. The Favorable, Marginal and Unfavorable rating bands do not change. This happens whether or not the age line appears.
Related Help Pages
Understanding Your Briefing
How to read and interpret each briefing section
Weather alerts banner
NWS watches and warnings shown above the WX Score
Hazardous Weather
Convective indices and thunderstorm detection explained
Convective Watch Scoring
SIGMET encounter timing, ledger dedup, and threat scores
Multi-Model Icing Analysis
How icing deductions and physics gates work
Wildfire Smoke
En-route plume overlays and VFR visibility scoring
Personal Minimums
Set the weather limits that drive your WX Score
Switch to IFR
See the WX Score under IFR when ceilings or vis crush a VFR briefing