A free skydiving weather tool that shows live winds aloft forecasts, helps plan jump run direction, and estimates freefall drift — built by a skydiver, for skydivers.
winDZaloft pulls live wind data from NOAA and Open-Meteo and presents it in a format designed for skydivers. Instead of reading raw aviation weather text, you get a clean table showing wind speed, direction, and temperature at each altitude relevant to a skydive — from the surface up through 24,000 ft.
The app also calculates suggested jump run direction and estimated freefall drift distance using the same method taught in the USPA Coach and Instructor courses.
NOAA publishes FD Winds four times per day at 00Z, 06Z, 12Z, and 18Z (UTC). There is a publishing lag of approximately 45–60 minutes after the cycle time. The data is not hour-specific — each forecast represents conditions for a ~6-hour window, called the "FOR USE" window.
The Issued time shown in the app is when NOAA generated the data. The Valid time is the reference time the forecast applies to. The For Use window is when the FAA considers the forecast current for aviation use.
winDZaloft shows a data freshness indicator (green/yellow/red) and a countdown to the next expected update so you always know how current your data is.
All altitudes are MSL (Mean Sea Level), not AGL (above ground level). If your dropzone is at 500 ft MSL, the 3,000 ft row represents winds about 2,500 ft above the ground.
Direction is where the wind is coming from, in degrees true. This matches aviation convention. Examples:
| Direction | Meaning | Wind arrow points |
|---|---|---|
| 270° | Wind from the west | Toward the east (↑ relative to north) |
| 180° | Wind from the south | Toward the north |
| 090° | Wind from the east | Toward the west |
| 000° / 360° | Wind from the north | Toward the south |
Shown in knots by default. You can switch to MPH or m/s using the toggle. As a quick reference: 1 knot ≈ 1.15 mph ≈ 0.51 m/s.
Temperature is in Celsius at each altitude. Temperature decreases with altitude in the standard atmosphere at about 2°C per 1,000 ft. Unusually cold temps at altitude can signal strong jet stream influence.
| Layer | Altitude | Why it matters |
|---|---|---|
| Surface | 0 ft (METAR) | Current observed winds on the ground — what you actually feel opening the door |
| Pattern | ~1,000 ft AGL | Canopy pattern and landing approach winds — interpolated from surface + 3k |
| Canopy | 3,000 ft | Under canopy after deployment — most relevant for canopy pilots |
| Climb | 6,000 ft | Lower freefall / Cessna exit altitude range |
| Freefall | 9,000 ft | Core freefall zone for most 10,500 ft loads |
| Exit Hi | 12,000 ft | Standard 13,500 ft exit — winds at or just below exit altitude |
| High Alt | 18,000 ft+ | High-altitude and HALO jumps; strong jet stream influence at this level |
The suggested jump run heading is calculated by averaging wind directions from the surface through 12,000 ft (surface, 3k, 6k, 9k, and 12k). This is the "line of flight" — the heading the aircraft should fly so that jumpers naturally drift along a consistent track from exit altitude down to the ground. This method follows the USPA SIM (Skydiver's Information Manual) approach used by instructors and coaches.
A reciprocal heading (180° opposite) is also shown, which represents the jump run flown in the opposite direction — sometimes used if the wind shifts between altitude levels.
Freefall drift estimates how far a skydiver will travel horizontally during freefall (before parachute deployment). The calculation uses the simplified Ranch equation:
drift (ft) = (avgWindKts ÷ 60) × 5280 × (freefallSeconds ÷ 60)
Where avgWindKts is the average wind speed across 3k–12k ft and freefallSeconds defaults to 60 seconds (approximate freefall time from ~13,500 ft). This is an estimate — actual drift depends on body position, exit altitude, deployment altitude, and wind variability.
Canopy drift estimates horizontal distance traveled under parachute from deployment to landing, using the average of lower-altitude winds and a configurable canopy descent time.
winDZaloft is an informational tool only. It does not replace the judgment of your S&TA (Safety and Training Advisor), Instructor, or Pilot-in-Command. Always defer to your dropzone's S&TA for official weather calls.
winDZaloft is built and maintained by SkyJunk, a skydiver and developer based in the US. The project started as a personal tool to make winds aloft data more readable and useful at the dropzone.
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