WX Score: How It Works
Understand how PlaneWX calculates your score, what triggers an unfavorable status, and how your personal minimums shape the assessment.
Overview
Your WX Score starts at 100 points and is reduced by deductions for weather conditions that don't meet your personal minimums and aircraft capabilities. It is not based on generic VFR/IFR standards. It reflects what matters for your flight, your aircraft, and your experience level.
Favorable (75 and up). Conditions meet your minimums. Plan confidently.
Marginal. Some conditions are close to your limits. Monitor closely.
Unfavorable. Conditions exceed your limits. Strongly consider postponing.
Automatic Unfavorable Conditions
Certain conditions are always unfavorable regardless of your score math. These are hazards that no personal minimums setting can mitigate:
Freezing Precipitation
- • Freezing rain (FZRA)
- • Freezing drizzle (FZDZ)
- • Freezing fog (FZFG)
- • Ice pellets (PL)
Unfavorable regardless of FIKI equipment
Convective Weather
- • Thunderstorms (TS, TSRA, TSGR)
- • Vicinity thunderstorms (VCTS)
- • Hail (GR)
- • Squalls (SQ)
Severe Hazards
- • Funnel cloud / tornado (FC)
- • Volcanic ash (VA)
- • Severe dust/sand storms (+DS, +SS)
Personal Limit Exceedances
- • Ceiling below your hard limit
- • Visibility below your hard limit
- • Crosswind exceeds your limit (all runways)
- • Icing exceeds your tolerance
- • Turbulence exceeds your tolerance
- • Any icing without FIKI equipment
The 12-Hour Rule
PlaneWX treats flights differently based on how far out they are. TAFs (Terminal Aerodrome Forecasts) are highly reliable within 12 hours but become uncertain beyond that.
Within 12 Hours
- Server-side pre-flight check runs against TAF data
- Hard limit exceedances = 0% score
- Hazardous weather phenomena = 0% score
- Comfort/limit zones checked with graduated penalties
- Server handles turbulence, icing, crosswind, and wind shear scoring
Beyond 12 Hours
- Most pre-flight checks wait until inside 12 hours
- When a TAF covers departure or arrival (up to 24h), server still scores TAF wind shear and crosswind. A hard violation can be 0%, not the 25% floor
- Otherwise no automatic 0%. Minimum floor of 25%
- Forecasts are uncertain. Conditions may improve
- Briefing auto-refreshes and re-scores as departure approaches
- AI scores icing and turbulence based on your personal limits
Why 25% and not 0%? Forecasts more than 12 hours out are based on models (GFS, NBM) and area forecasts (AFDs), which are less precise than TAFs. A 0% score would suggest certainty that doesn't exist. The 25% floor signals "unfavorable but uncertain" (except when a covering TAF already names wind shear or crosswind over your limits). Your briefing will automatically re-score with more accurate data as departure approaches.
Scoring Categories & Maximum Deductions
Each weather category has a maximum deduction cap. No single factor can take more than its cap, and the system validates this server-side.
Route-coverage thunderstorm deductions and an en-route Convective SIGMET are assessments of the same air mass, so they're capped together in aggregate rather than added on top of each other: combined, en-route convective billing is limited to 40 points, but never below whichever single deduction is strongest, so a -50 Convective SIGMET alone still stays at -50, not -40. This applies only to en-route billing; a thunderstorm tied to your departure or arrival airport is a different air mass and is scored (and capped) on its own.
| Category | Max Points | When It Applies |
|---|---|---|
| Ceiling below minimums | -40 | Forecast ceiling at departure or arrival is below your hard limit |
| Visibility below minimums | -40 | Forecast visibility at departure or arrival is below your hard limit |
| Icing (no FIKI) | -40 | Any forecast icing without FIKI equipment |
| Icing (exceeds limit) | -15 to -50 | Severity exceeds your stated icing tolerance (even with FIKI) |
| Icing (within limit) | -5 | Icing at or below your tolerance (caution only). Severity derived from multi-model analysis (regional hi-res + GFS + ECMWF by geography) |
| Severe icing | -50 | Severe icing exceeds any pilot limit |
| Warm nose + freezing rain (model soundings) | Unfavorable | An above-freezing layer over sub-freezing air, confirmed by corroborating evidence (the structure that produces freezing rain and freezing drizzle). FIKI approval does not cover SLD. The Appendix O certification basis is confined to transport-category aircraft, so assume yours is not approved unless its AFM says so. FIKI does not mitigate SLD. |
| SLD potential present (CIP/IFI) | -10 to -30 | Caution sized by how strongly large droplets are indicated, up to -30. The affected phase sets the bar for whether a reading counts (cruise is held to a higher bar than climb or descent). Requires at least light icing in the same layer. Applies to all aircraft regardless of FIKI. Product potential alone does not force a 0% (the field is an uncalibrated indicator, not a probability). |
| Thunderstorms | -40 | Forecast during your flight window (TAF TEMPO/FM) |
| Convective SIGMET | -50 | Active convective SIGMET valid during your flight |
| Turbulence (exceeds limit) | -10 to -30 | Severity exceeds your stated turbulence tolerance |
| Turbulence (within limit) | -5 | Turbulence at or below your tolerance (caution only) |
| Crosswind | -15 | Server-calculated from TAF wind + runway data (when a TAF covers departure or arrival) |
| Headwind impact | -5 to -15 | Flight time increased 15-25% (-5), 25-40% (-10), >40% (-15) |
| SIGMET (non-convective) | -15 | Active SIGMET along your route |
| G-AIRMET IFR (VFR trip) | 0% / -30 | An IFR G-AIRMET counts when its area comes within 25 NM of your route at the time you pass it. Today, on a VFR trip, that is a hard stop whether or not your route enters the area; when it does not, the briefing says so and gives the distance. PlaneWX measures the 25 NM to the nearest corner of the area. Exception: arrival only, when the arrival airport has its own (not proxy) TAF showing VFR at your ETA (including TEMPO and PROB groups), it becomes a -30 Marginal caution instead. From 25 to 50 NM it is a smaller caution of 15 to 25 points. |
| Mountain obscuration (VFR) | -50 | G-AIRMET Sierra MTN OBSCN directly on your VFR route |
| Approaching minimums | -10 | Ceiling within 500 ft or visibility within 1 SM of your limit |
| Wind shear | -10 to -20 | Graduated penalty based on your wind shear speed limits |
| Density altitude | 0* | Caution banner only (not a score ding). *Score hit only when runway performance criteria fail for types that run POH math (e.g. TBM 900) |
NBM gusts are checked against Max Ground Operations Wind (penalty only; gust-only overage at a lower rate than steady wind). In the roughly 12 to 72 hour range, the tri-source forecast can also use NBM gust in the crosswind check when NBM and MOS wind directions align. Crosswind uses the best aligned runway that meets your aircraft's minimum runway length.
Comfort vs. Limit (Soft / Hard Minimums)
PlaneWX uses a two-tier minimums system for graduated scoring:
Comfort (Soft Limit)
Your preferred conditions. Exceeding your comfort level puts you in the caution zone (yellow). The score penalty is proportional to how far into the zone you are.
Example: Ceiling comfort 2000 ft, limit 1000 ft. A 1500 ft ceiling is in the caution zone.
Limit (Hard Limit)
Your absolute maximum tolerance. Exceeding your limit is unfavorable (red). Within 12 hours, the score drops to 0%. Beyond 12 hours the 25% floor applies, unless a covering TAF wind-shear or crosswind hard limit is exceeded (then 0%).
Example: Ceiling limit 1000 ft. A 900 ft ceiling is unfavorable.
At your limit = caution, not unfavorable. If you set your turbulence limit to "Moderate" and the forecast shows moderate turbulence at cruise, that's a -5 caution, not unfavorable. You set that limit because you accept it. Unfavorable only triggers when cruise conditions exceed your stated limit. Moderate bumps confined to climb or descent (cruise still within comfort) are a small residual caution, not a full cruise Moderate hit.
How Aircraft & Profile Affect Your Score
FIKI Equipment
Aircraft with FIKI (Flight Into Known Icing): moderate icing within your limit = -5 caution. Aircraft without FIKI: any forecast icing = -40 unfavorable.
Aircraft Overrides
Aircraft-specific limits (crosswind, turbulence, icing) override your personal minimums. The more restrictive value always wins. Aircraft overrides are shown with a plane icon () in the Personal Minimums bar.
Flight Rules
VFR and IFR flights use separate ceiling/visibility minimums from your profile. VFR flights also check for IFR conditions and mountain obscuration (G-AIRMET Sierra) along the route. An IFR G-AIRMET within 25 NM of your route is a hard stop for VFR today, even when your route does not enter the area; if it covers only arrival and that airport's own TAF shows VFR at your ETA, PlaneWX applies a Marginal caution instead of zeroing the score. Departure and en route stay hard stops. From 25 to 50 NM it is a smaller caution.
What Does NOT Affect Your Score
PlaneWX is strict about only deducting for confirmed, product-backed conditions. These items are mentioned in your briefing for awareness but do not reduce your score:
- ✓Forecast uncertainty or distance to departure
- ✓Regional patterns without product confirmation (e.g., "gusty winds on ridges")
- ✓Expired TEMPOs, G-AIRMETs, or SIGMETs that end before your flight
- ✓Old PIREPs that won't persist to departure time
- ✓Sky cover percentage alone (OVC does not mean a low ceiling without a height value)
- ✓Temp/dewpoint spread or fog risk (awareness only unless visibility is below minimums)
- ✓Thunderstorm mentions in WPC outlooks at 3+ days (scored as caution, not unfavorable)
- ✓Nearby airport reports near your destination. When you arrive within about 3 hours of the briefing and your destination has no TAF of its own, or its TAF doesn't show fog, mist, or IFR at your ETA, Ceilings & Visibility can list up to 2 airports within about 30 nm whose latest report (from the last 90 minutes) shows fog, mist under 3 SM, or IFR. For example: “KMIE, 13 nm, reporting 1/4 SM fog. Not scored.” These lines are a heads-up for your GO / NO-GO call and never change your WX Score.
Score Breakdown & Validation
- • Click Score Breakdown in your briefing to see exactly which factors are deducting points
- • Server-side validation ensures no single category exceeds its deduction cap
- • If a briefing section is marked "marginal" or "unfavorable" but has no matching deduction, the system adds one automatically
- • The WX Score is cross-checked against the Personal Minimums Check for consistency
- • For flights within 12 hours, the pre-flight check results take precedence over AI scoring
- • From 12 to 24 hours, TAF wind shear and crosswind server checks take precedence when a TAF covers that airport
- • Static runway length/surface fitness runs on every briefing (including beyond 12 hours) as a caution banner only: no WX Score floor or deduction for runway alone; weather-dependent checks stay time-gated and scored on the same schedule