Weather Probe-
Hunter – Exotic pastime

Do you know a weather probe hunter and what the followers of this somewhat exotic hobby engage in?

On this page we explain what makes weather probe hunting so interesting. And we show which possibilities there are to track weather probes and which equipment you need - or may already have.

Foto: DG1HP

Tracking, scouting, collecting

Essentially, it involves tracking trajectories, reading weather data, and collecting weather probes that have landed back on the ground. One would think the biggest target audience for this hobby would be radio amateurs, SWLs, and electronics hobbyists. Sure, among them there are many a prominent weather probe hunter who approaches matters with a great deal of expertise and technical effort. Certainly, a certain soft spot for radio technology plays a role, but the majority of weather probe hunters are not licensed radio amateurs, but simply radio enthusiasts interested in meteorology and aerology (high-altitude meteorology). The pool of people is larger than one might think, as a majority of weather probes are recovered specifically by weather probe hunters.

One receives a deeper insight into this special field of interest only if one asks a passionate weather probe hunter: It has something of Geocaching extremely", says Eilert Menke, DL9BDM. "One becomes acquainted with with difficulty accessible areas off the roads and ways and meets during the final search actions inevitably also other participants." And what is the motivation?

In addition to the technical interest, it is the sporting aspect, the idea of competition and the rise in the ranking of weather probe hunters on Many a weather probe hunter has an extensive collection hanging in his hobby room as trophies under the ceiling.

What is a weather probe - technology and tasks

The carrier of the weather probe is a stratospheric balloon filled with the inert gas helium and made of highly elastic natural rubber. Under the balloon, in newer models already integrated into the balloon, follows the folded parachute. On the so-called unwinder, a 60 m long, tear-resistant thin plastic cord is wound up. At its lower end, it carries the radiosonde encapsulated in a protective housing made of Styrofoam with the sensor unit for temperature and humidity attached to the outside. The large distance is necessary to exclude any influence of the balloon on the measurements.

The weather probes are equipped with functions and sensors for recording the following measured values: A GPS module is used for exact location determination. However, the GPS data are only transmitted as GPS RAW data, not as classical coordinates. Airspeed, altitude and rate of climb are calculated by the GPS. Corresponding sensors measure the air pressure, temperature, relative humidity and dew point. All these data are transmitted digitally in FM narrow mode (narrowband FM) on a frequency assigned to the probe in the frequency range 400 to 406 MHz, with a transmitting power of 50-60 mW. All electronics are SMD on a single board and are powered by two lithium batteries with 3 V operating voltage.

At an altitude of 31 to 35 km and a covered horizontal distance between a minimum of 10 up to an average of 300 km, in individual cases up to 1000 km, the balloon envelope, which in the meantime has been inflated to the size of a single family house, bursts. After a stretch of free fall, the parachute opens and the braked descent begins. In the descent, depending on wind direction and wind strength, the probe can cover again the same distance as in the ascent to the final location. Due to the prevailing wind directions in many areas, the later discovery sites are predominantly in a preferred direction to the launch site. On average, a weather balloon spends three hours in the airspace from launch to landing.

So-called ozone probes are much larger, technically more complex and are launched once a week. Anyone who finds the remains of one of these probes is asked to contact the weather service. In exchange for payment of a finding fee, the return of the ozone probe is requested.


Looking back at the old technology

In the old days, from the 1950s to the 1980s, weather probes still operated with analog technology in the 27 MHz, and between 40 to 50 MHz frequency ranges. The air pressure was measured with a mechanical can barometer, and the altitude above the ground was also determined via this value. Thermometer and hygrometer provided the temperature and humidity readings. A quartz-controlled transmitter was modulated in pitch (A2) analogous to the measured value. The probes did not provide much more in the way of data. All other findings and information, as they are directly transmitted by the probes today, such as exact altitude, rate of climb, speed and direction, could only be obtained by radar from the ground at that time. For this purpose, the weather balloons carried a radar reflector at the lower end, with which their flight paths were tracked by radar from the launch and location of the respective weather service.

Tasks and responsibilities of the weather services

"In Germany, there are about 30 locations of the German Weather Service DWD and the German Armed Forces where weather probes are launched regularly. The schedule is internationally regulated: At least twice daily, during the day at 12:00 UTC and at night at 00:00 UTC. In addition to the general data for the weather service, the Bundeswehr (German Army) also collects other weather data for its own flight operations. Worldwide, there is a network of more than 600 weather stations from which weather balloons are launched several times a day. The data provided by the weather probes form an essential basis for producing our weather forecasts.


Current weather probes

The Vaisala RS41-SGP weather probe is the standard model and is the most widely used by weather services in DL, EU as well as worldwide. Another manufacturer of weather probes is the Graw company, present on the market with the DTM17 model.

A sticker of the DWD informs about the purpose and further use:

This radiosonde is used to measure air temperature, humidity and air pressure as well as wind direction and wind speed and was launched by the German Weather Service (DWD)

The measuring device is no longer needed and can be disposed of via the local waste system (electronic scrap).

In case of damage , please contact the e-mail address: [email protected], stating the serial number

img DWD 1/2023
(Abbildung ähnlich)

Necessary hardware for weather probe hunting

Receivers, handheld scanners, handheld radios, and directional antennas are indispensable tools for a successful weather probe hunt, especially in what is known as the last mile, or the last few meters before the site is found on the ground.

Theoretically, it is possible to locate a probe without any other technical aids by following its flight path from home through radiosonde monitoring by the DWD at, alternatively at or with the radiosonde tracker from SQ6KXY,, until the final landing. Afterwards, one could use this data to visit the site to recover the probe. But just rather theoretically and with a lot of luck, if one is the only one on the case". In addition, a certain inaccuracy remains and the terrain can be very confusing.

The minimum equipment on site is a handheld scanner or radio that covers the 400-406 MHz frequency range, has a usable S-meter display (analog or bar graph), an attenuator, and a unscrewable rubber helical antenna.

For a first bearing, it is useful to put a small directional antenna on the scanner or handheld radio. Here a HB9CV for the 70 cm band or a small log-periodic directional antenna are particularly suitable. When aiming to the location of the probe that is still transmitting, the attenuator is used first. If the probe is still not located, the antenna is unscrewed in the absolute close range on the proverbial last meters.

This is the sporty, but now technically obsolete, classic method of taking bearings. Other tools for recovering a weather probe are a fiberglass telescopic rod, and small, lightweight binoculars for close range.

Man Hand Image

Probe search with TTGo and smartphone

Currently, many weather probe hunters use a TTGo along with an Android phone to display the trajectory for tracking and searching. This eliminates the need for conventional tracking by taking a bearing of the probe signal at close range.

A TTGo module programmed for probe reception with firmware receives the signal from the weather probe via an antenna in the 400 to 406 MHz range. The data can be read out on a display and the flight path can be shown on a live map. This makes it possible to receive weather probes from home without a subsequent search and recovery of the probe. If this equipment is used in a mobile or portable way, it is possible to locate the probes via the location coordinates, without a classical bearing of the signal. A LoRa tracker can transmit the data wirelessly directly to a smartphone. Detailed info and the corresponding software for this technology are available at

What is LoRa and LoRaWAN?

LoRaWAN = Low Power Wide Area Network, is a radio technology in the ISM ranges 433/868/915 MHz and is used for data transmission in the so-called Internet of Things. This network is formed by the nodes (end devices) and the gateways (base stations). They forward the data between the end devices and the network servers. forward. The connection between end devices and gateways is either wireless via frequencies in the ISM band ranges or via mobile radio frequencies. Gateways and network servers communicate via IP connections on the Internet. For a more in-depth look at the terms and functions of this complex technology, visit our LoRaWAN page at “LoRa/Helium antennas”.

Man Hand Image
Man Hand Image

Further use of the weather probes

What can you do with weather probes other than collect them?

Some radio amateurs among the weather probe hunters reprogram the probes for a frequency in the 70-cm amateur radio band. This requires no hardware intervention; the probes have an interface for reprogramming! They are then used again on a balloon as part of amateur radio projects. For the Vaisala RS41 weather probe contains detailed conversion instructions. Otherwise the small SMD board offers hardly anything to cannibalize. Only the two lithium batteries are coveted, as they are still charged to a large extent after a single, relatively short use.

Unterstützung Für Sondenjäger

Support by special software

Under the following links, weather probe hunting supporting software is available for download:

Supporting websites on the Internet

Radiosonde monitoring on maps in real time:

Are there interest groups for this hobby?

Weather probe hunters tend to be lone wolves and are in competition with each other. That a weather probe is searched for and recovered as a team is certainly extremely rare. Therefore weather probe hunters are hardly organized and there is, apart from a registration and the member area on, in the actual sense no association or a representation of interests. Thus this leisure activity has something of "unofficial and secretive".

RadioSondy Registrierung
Contribution to environmental protection

The specimens that are not found, unfortunately, remain in nature with probe, parachute and carrying cord. The balloon cover made of natural rubber does rot quickly and is therefore biodegradable. But the remains of the parachute envelope, which cannot be digested by animals, and in particular the thin, tear-resistant carrying cords made of plastic, pose a considerable danger to wildlife. Thus, the weather probe hunters also contribute to environmental protection with their leisure activity. Further accidental finds by walkers or property owners are disposed of anyway according to the information on the sticker.



What happens to weather probes that are found? Do you have to return them?

No, see text on sticker on probe housing.
Exception, ozone probes: They must be returned!

How often are weather probes launched?

In Germany twice a day, at 00:00 and 12:00 UTC. In other countries, up to four times a day, at 6-hour intervals at 00:00; 06:00; 12:00 and 18:00 UTC.

Who is allowed to listen to the transmissions of weather probes?

The reception and reading of the data is not subject to any restriction and is available to everyone.