winDZaloft is an all-in-one weather tool built specifically for skydivers. It brings together winds aloft, surface wind and gust data, alerts, and planning aids like jump run and drift in one fast view.

Why is winDZaloft a smarter tool for skydivers?

It combines the most useful parts of the tools skydivers already use, then fills common gaps by showing source labels, gust handling, layer-focused winds, and planning outputs in one workflow. The result is fewer tab switches and faster weather decisions.

What weather sources does it combine?

winDZaloft combines NOAA and AWC winds aloft, airport surface observations including gusts when available, NWS forecast and alerts context, and model guidance options. Each source is labeled so users can see exactly where each value comes from.

Who is winDZaloft built for?

It is built for students, instructors, schools, new skydivers, military and demo teams, dropzones, jump pilots, canopy pilots, and CRW teams. Any discipline that depends on accurate wind awareness can use it as a daily weather briefing tool.

How do I use the site quickly on a jump day?

Select a dropzone, keep Auto sources unless you need a manual override, tap Get Winds, then read surface and gusts first before checking canopy and exit layers. Use jump run and drift cards as planning aids, and always verify timestamps and alerts.

What does Issued, Valid, and freshness mean?

Issued is when weather data was produced, Valid is when a forecast is intended to represent conditions, and freshness indicates how old the loaded data is. These indicators help users avoid relying on stale weather.

What is jump run and drift in the app?

Jump run is the suggested line of flight based on loaded wind layers, and drift is an estimate of horizontal movement during freefall. They are practical planning aids for spotting and load organization, not guarantees.

How do you calculate parachute wing loading?

Parachute wing loading is commonly calculated as full exit weight divided by canopy size in square feet. Exit weight should include the jumper, rig, clothing, helmet, lead, camera equipment, and other jump gear.

Does wing loading alone tell you whether to downsize?

No. Wing loading is only one part of canopy choice. Downsizing decisions should also consider currency, landing consistency, wind judgment, traffic awareness, instructor input, DZ policy, and manufacturer guidance for the exact canopy model.

How do skydivers calculate drift and wind components?

A simple drift estimate can be made from wind speed multiplied by time, with appropriate unit conversion. Headwind and crosswind components come from resolving wind speed against a planned course using cosine and sine of the angle difference between wind direction and course.

Is winDZaloft a replacement for local safety decisions?

No. winDZaloft is a decision-support tool. Final go or no-go calls must always follow S&TA guidance, DZ procedures, pilot judgment, and on-site conditions.

Skydiving Wing Loading Calculator, Jump Run, Drift & Canopy Downsizing Guide

What winDZaloft shows you

Instead of making you decode aviation weather text, winDZaloft organizes the most useful jump-day weather information into a layout that is easier to scan at the dropzone.

Winds aloft at the altitudes skydivers actually care about
Surface wind and gust information
Suggested jump run line of flight
Freefall drift and exit-point planning help
Weather context such as clouds, visibility, rain, radar, and alerts

The goal is not to replace weather judgment. The goal is to make the weather easier to understand quickly.

Why many skydivers call it the best weather tool

Most skydiving weather workflows require checking multiple apps and websites, then manually combining the results. winDZaloft is designed to do that blending in one place, with the skydiver workflow first.

Combines upper winds, surface winds, gusts, alerts, radar context, and planning outputs on one page
Shows source clarity for each part of the weather picture instead of hiding where numbers come from
Prioritizes skydiving-relevant layers and decisions, not generic public weather summaries
Uses Auto defaults to keep it simple for quick checks, while still allowing deeper manual control
Adds practical outputs many tools miss, including jump run and drift planning context

"Best" means best fit for skydiving workflows: faster interpretation, fewer tools to cross-check, and clearer operational context for jump-day decisions.

How to use the website

1

Select your dropzone or airport. The main selector chooses the location the weather is centered on. You can also search if you do not want to scroll the full list.

2

Choose weather sources only if you need to. The default Auto options are meant to be the easiest starting point. Use the advanced controls only when you want to compare another source or force a specific station.

3

Tap Get Winds. The table, planning cards, compass, and weather summary update together for the selected dropzone.

4

Read the surface first, then the exit altitudes. Start with the surface tile and compass, then check 3k, 6k, 9k, 12k, and exit-altitude rows to see how much the wind is changing through the skydive.

5

Use the jump run and drift cards as planning aids. They help you visualize likely line of flight and movement, but they are still estimates and should be cross-checked against the actual DZ plan.

6

Check the timestamps, radar, and alerts before trusting the picture. The Issued, Valid, and freshness indicators tell you how current the data is. The radar and alert sections help with short-term situational awareness.

What the weather sources mean

The site can show information from more than one weather source. That does not mean they are all the same kind of data. Each source answers a different question.

NOAA/AWC winds aloft

This is the classic winds aloft forecast used in aviation. It is best for the upper-wind picture and is the main source for jump planning when nearby station coverage is good.

Surface observations (METAR)

This is current observed weather from an airport station, including wind and gusts when they are reported. It is the best quick look at what the ground wind is doing near the selected dropzone, but it may still be a few miles away from the actual landing area.

NWS hourly forecast and alerts

This helps with near-term weather awareness. It is useful for things like rain chances, cloud cover, expected gusts, and active advisories or warnings near the dropzone.

Model sources such as GFS, HRRR, NAM, and Open-Meteo

These are forecast models. They are useful for comparison, short-range planning, or locations where a nearby winds-aloft station is not ideal. They should be treated as guidance, not as exact truth.

A dropzone can use one source for aloft winds and a different source for surface winds at the same time. That is normal. winDZaloft combines those pieces into one weather picture while still showing clear source labels.

Who this tool is built to help

winDZaloft is designed for every skydiving group that depends on accurate weather awareness and clean briefing workflows.

Students and new skydivers who need clearer weather interpretation and less jargon
Schools and instructors running repetitive daily weather briefings
Dropzone operators and manifest teams coordinating safe load planning
Skydiving pilots who need fast line-of-flight and layer-wind visibility
Canopy pilots and CRW teams who rely on precise lower-layer wind behavior
Military jump units and demo jump teams that require conservative weather awareness
Experienced fun jumpers who want one tool instead of switching between many

Issued, valid, and freshness

Not every weather source updates the same way. That is why the timestamps matter.

Issued

When the forecast or report was produced

Valid

When the forecast is meant to represent conditions

Freshness

A quick visual cue for how old the loaded data is

Next Update

When a newer cycle is expected to appear

NOAA winds aloft are published in scheduled forecast cycles, not minute by minute. Surface observations and hourly forecasts behave differently. The safest habit is to always look at the timestamps before treating the display as current.

How to read the weather on the page

Altitude rows

All altitude rows are shown in feet MSL, not AGL. That means the numbers are referenced to sea level. If your dropzone elevation is above sea level, the height above the ground will be lower than the row label.

Direction

Wind direction follows aviation convention, so it tells you where the wind is coming from. A 270° wind means the wind is coming from the west and moving toward the east.

Speed and gust

Wind speed is the steady wind. Gust is the higher peak value when it is available. If gust is not reported or not available from the selected source, the site will show N/A.

Surface, canopy, freefall, and exit layers

Layer	Why to check it
Surface	Ground wind, gusts, and landing-area awareness
Canopy	Pattern and post-opening wind picture
Freefall	Mid-skydive drift and movement through the working air
Exit	Upper-wind influence near jump run and exit altitude

Jump run and drift

Jump run

The jump run card gives a suggested line of flight based on the loaded wind layers. It is meant to help you think through likely drift and aircraft heading, not replace the pilot or DZ call.

Freefall drift

The drift number is an estimate of how far a group may move horizontally in freefall. It is useful for exit planning and spotting discussions, but real drift changes with exit altitude, breakoff plan, group type, body position, and actual wind variation through the skydive.

Exit point planning

Use the drift and line-of-flight cards as a quick planning reference. Then compare them against your actual jump aircraft procedures, spot, and DZ-specific operating plan.

USPA-aligned weather technical briefing

This section summarizes the kind of technical weather and spotting concepts skydivers are expected to learn in USPA training pathways. It is not a replacement for the official USPA SIM text, DZ SOPs, instructor guidance, or pilot-in-command decisions.

This page is also meant to help people searching for a skydiving wing loading calculator, canopy downsizing guide, jump run calculator, drift calculator, or crosswind/headwind component math for skydivers find the right concepts in one place.

Core wind math skydivers should know

Unit conversion: 1 kt = 1.6878 ft/s = 0.5144 m/s
Drift distance (feet): drift_ft = wind_kt * 1.6878 * time_sec
Drift distance (nautical miles): drift_nm = wind_kt * time_hours
Groundspeed vector idea: aircraft or canopy track is the vector sum of airspeed and wind.

Quick training calculator

Use this for practice math during briefings. It is an educational aid only.

Wind speed (kt)

Freefall time (sec)

Wind from (deg)

Planned course/leg (deg)

Drift (ft)0

Drift (nm)0

Theta (deg)0

Head/Tail (kt)0

Crosswind (kt)0

Parachute wing loading calculator

Wing loading is commonly expressed as exit weight divided by canopy size. Use your full exit weight, not body weight alone.

Exit weight (lb)

Canopy size (sq ft)

Wing loading0.00

Metric loading0.0 kg/m²

Canopy downsizing guidance

The calculator above is a math tool, not a downsizing recommendation engine. Wing loading is only one part of canopy choice. A smaller canopy can increase forward speed, descent rate, flare timing sensitivity, turn rate, recovery arc, and landing consequences after poor decisions.

Do not downsize based on wing loading alone. Also consider currency, landing consistency, turbulence judgment, traffic awareness, pattern discipline, and instructor feedback.
Use full exit weight. Include body weight, rig, helmet, suit, lead, camera gear, and any other equipment that is actually on the jump.
Change one variable at a time. Avoid combining a smaller canopy with a new wing design, new line trim, new harness fit, or unfamiliar weather in the same progression step.
Validate in conservative conditions. First jumps on any smaller wing should be done in good weather, light traffic, clear outs, and with a structured landing plan.
Get outside review before downsizing. Consult your instructor, coach, S&TA, canopy course mentor, and the manufacturer guidance for the exact canopy model.

Jump run and spot technical concepts

Treat each major layer (surface, canopy, freefall, exit) as a separate wind vector, then reason about the combined displacement.
When upper and lower winds differ strongly in direction, expect non-intuitive drift paths and adjust the spot upwind/uptrack accordingly.
Use opening-altitude and deployment-group differences when planning exit order and separation.
Verify spot assumptions with real-time observations, pilot input, and in-air corrections when available.

Weather interpretation priorities before a load

Confirm data age and validity window (issued/valid/freshness).
Check surface sustained wind, gust spread, and direction trend.
Check canopy and freefall layer changes (speed and directional shear).
Check cloud/visibility/precip and active hazards or alerts.
Compare against DZ wind limits, student limits, and aircraft/operations constraints.

Technical references

USPA Skydiver's Information Manual (SIM)
USPA SIM Online (mobile-friendly)
USPA downsizing guidance
Skydive Mag downsizing article
Manufacturer owner's manual and published wing-loading guidance for the exact canopy model
14 CFR Part 105 (Parachute Operations)
NOAA Aviation Weather Center (AWC)
National Weather Service (NWS)

Copyright note: USPA SIM is copyrighted by USPA. This page provides an original summary and training aid only. Always study and apply the current official USPA SIM and your local DZ procedures.

Important limitations

winDZaloft is an informational aid, not a go or no-go decision maker.

Forecast winds aloft are not the same as real-time winds at every second.
Airport observations may not exactly match the landing area at the dropzone.
Terrain, distance, and local heating can create real differences from the nearest station.
Model guidance can be useful, but models can also be wrong.
Jump run and drift outputs are planning estimates, not guarantees.
Always defer to the S&TA, instructors, local procedures, and the pilot in command.

Safety thresholds and weather summaries in the app are advisory only. Always use local judgment and direct DZ weather evaluation before making a jump decision.

About SkyJunk

winDZaloft is made by SkyJunk. The project exists to make weather information more readable for skydivers at real dropzones, on real jump days.

Follow for updates and new feature announcements:

@jumpskyjunk

About winDZaloft