Sonde Predict

➜ Project page: oh2gba.github.io/SondePredict — downloads, screenshots, how accurate it is, and the user manual.

Predicts where a radiosonde will land after its weather balloon bursts, from upper-air wind forecasts (MET Norway's MEPS in the Nordic area, ECMWF or another global model elsewhere), so you can tell at a glance whether a launch is worth hunting. Shows the track, burst, landing point and a 95% landing area on a map, with the distance and direction from your own location, in 3D over the map and as an altitude profile; batch predictions for several days and GPS/phone (GPX) export.

Download

System	Download
Windows 10 / 11 (64-bit)	Installer · Zip (no install)
Linux (x86-64)	AppImage — make it executable (chmod +x) and run it

These links always give the newest version; older ones are on the releases page. How to install, use and uninstall it is in the user manual (PDF), which is also built into the app (Help → User manual, F1).

Sonde Predict 5 is a C++20 / Qt 6 rewrite of Sonde Predict v3 (2016–2022), which was Windows-only. Coming from v3? File → Import Sonde Predict v3 settings brings over your locations, balloon settings and batch schedule.

Building from source

The rest of this page is for developers. PLAN.md describes the design and the roadmap; the recovered source of v3 is in recovered/.

Needs CMake ≥ 3.21, Ninja, a C++20 compiler, Qt ≥ 6.5 (Core, Network, Sql, Widgets, Quick, QuickWidgets, Location, Positioning, Test) and the OpenGL development headers.

cmake -S . -B build -G Ninja -DCMAKE_PREFIX_PATH=".toolchain/Qt/6.11.3/gcc_64;.toolchain/sysroot/usr"
cmake --build build
ctest --test-dir build --output-on-failure

Then start the app (sp-cli, the command-line predictor, is in build/src/cli):

./build/src/app/sondepredict

Packages and releases

• Linux: packaging/linux/build-appimage.sh <qt-prefix> builds a self-contained AppImage.
• Releases: pushing a v* tag runs .github/workflows/release.yml, which builds the Windows installer and zip and the AppImage and publishes them as a GitHub release.
• Manual: after editing docs/manual/user-manual.md, regenerate the PDF with sondepredict --manual-pdf docs/manual/user-manual.pdf (add QT_QPA_PLATFORM=offscreen on a machine without a display).

Command line

./build/src/cli/sp-cli --launch 60.814,23.499,104 --time 2026-10-23T11:15 --home 60.17,24.94

Times are UTC. --help lists the balloon settings (ascent rate, burst altitude, descent model), --csv writes the track, and --compare checks a prediction against a received flight saved by RS41Tracker.

Coming from v3? Import your old settings once, then use location names:

./build/src/cli/sp-cli --import-v3 /path/to/sonde_predict/config.ini

./build/src/cli/sp-cli --launch Jokioinen --home "Home, Espoo" --time 2026-10-23T11:15 --save

--locations lists saved locations and --list the saved predictions. --batch runs the batch set up in the app, --gpx writes the result for GPS apps, and --export 3,5 --gpx out.gpx exports stored predictions. Settings live in ~/.config/SondePredict/sondepredict.ini (Windows: %LOCALAPPDATA%\SondePredict), predictions in ~/.local/share/SondePredict/predictions.sqlite.

Wind data: in the Nordic countries and the Baltic, MEPS (2.5 km, 65 model levels) straight from MET Norway's THREDDS server (free, no quota), averaged with a global model (ECMWF IFS by default) from the free Open-Meteo API (non-commercial use; see the quota note in PLAN.md); elsewhere and beyond 66 hours, the global model alone. How the models compare with real soundings is in tools/validation.

Licence

Sonde Predict is free software under the GNU General Public License v3.0. Weather data: MEPS by MET Norway (CC BY 4.0); global models by Open-Meteo.com (CC BY 4.0); map data © OpenStreetMap contributors.