Frequently Asked Questions - FAQ

No. XC Therm is a so-called Progressive Web App (PWA). This means that XC Therm runs directly in the browser, but can be saved on the smartphone's home screen just like an app and then behaves just like an app from the App Store or Google Play.

The ICON-D2 wind and weather forecasts from XC Therm can be integrated into any website via iFrame. A detailed guide can be downloaded here.

For technical reasons, however, the thermal forecasts cannot be integrated into other websites.

The philosophy of XC Therm is to provide pilots with all the necessary tools so that they can make their own decisions. For this reason, XC Therm does not provide explicit wind or foehn warnings, nor recommendations on where to fly.

Based on the user-friendly high-resolution thermal, wind, and weather forecasts, pilots can form their own picture and determine which area is best for them based on their own flying skills.

To collect feedback on XC Therm in one central place, there is a forum for all XC Therm users.

Since this forum is independent of the regular website, a separate login is required. Each new forum participant must be approved by an admin after registration to ensure the quality of the forum (spam, bots...).

Visit the forum at forum.xctherm.com.

You can change your subscription yourself. To do this, go to Settings - Subscription - Manage Subscription - Update Subscription in the map and select the desired subscription. If you have a promotion code, you can redeem it there by following this guide.

If a subscription is changed to a larger one during the term, the existing subscription will be canceled and the unused portion of the old subscription cost will be deducted from the new subscription cost. The selected payment method will automatically be charged with the difference. The new subscription is then valid for a full year again.

Please note that upgrading to a larger subscription is possible at any time, while downgrading to a smaller subscription can only be done at the time of subscription renewal. Also note that the change always happens immediately and not at the end of the current subscription period.

You have received a promotion code (gift voucher or group discount) and want to redeem it? Then proceed as follows:

Case 1: You do not yet have a running subscription

Register with XC Therm and confirm your email address. Then select a subscription on the subscription page.

1. Select "Add promo code" on the payment page and enter your promotion code.
2. Click the "Apply" button to apply the code.
3. The price will be automatically adjusted and you can proceed with the payment.

If your payment fails and the window no longer shows the reduced price, do not proceed. The promotion code must then be manually re-entered by us. Write us an email to with the promotion code.

Case 2: You have a running subscription and want to upgrade to a larger subscription

Go to Settings - Subscription - Manage Subscription - Update Subscription in the map and select the subscription of your choice. Then follow the instructions as in Case 1.

Case 3: You want to apply your promotion code to the automatic renewal of your subscription

1. Write an email to with the promotion code.
2. We will store the promotion code on your account.
3. When your subscription is renewed, the promotion code will be automatically applied.

Important: Promotion codes cannot be applied retroactively, so you must enter the promotion code before paying or renewing your subscription.

You can enable or disable automatic renewal of your subscription yourself. To do this, go to Settings - Subscription - Manage Subscription - Cancel Subscription in the map.

Although the renewal of your subscription is disabled, you can continue to use XC Therm normally until the current subscription expires. If you later decide to enable automatic renewal again, you can do so at any time.

Our standard payment methods are credit card and PayPal. After payment, the subscription is automatically activated.

It is also possible to pay by bank transfer / prepayment. Follow this guide.

If you want to pay with TWINT, or other instant payment methods (Apple Pay, Google Pay, EPS, Sofort, Cartes Bancaires ...), follow this guide.

Please proceed as follows:

1. Transfer the correct amount to our account (account details below).
2. Write an email to with the name of the subscription and account holder, desired subscription, and possibly promotion code.
3. We will activate your subscription within 24 hours of receiving the payment.
4. If this does not happen, contact us via .

EURO account

Account holder: XC Therm GmbH
BIC: TRWIBEB1XXX
IBAN: BE54 9671 6197 4097
Bank address: Avenue Louise 54, Room S52, Brussels, 1050, Belgium

CHF account

Account holder: XC Therm GmbH
IBAN: CH18 0900 0000 6168 5473 5

TWINT Apple Pay, Google Pay, EPS, Sofort, Cartes Bancaires do not support recurring payments and therefore cannot be used for direct subscription purchases. Proceed as follows:

1. Buy a voucher for the subscription of your choice.
2. You will receive an email with the promotion code associated with your voucher.
3. Redeem this promotion code. Follow this guide

Yes, we offer discounts on annual subscriptions for groups of 10 or more people.

If you are a member of a club or association with an active XC Therm group discount promotion, contact the board of your club to receive a personal promotion code and follow this guide to redeem it.

If you want to activate a new group discount promotion for your club or association, you will find all the information you need here.

The amount of the group discount depends on the number of annual subscriptions sold within a calendar year (see table below). At the beginning of the year, the group discount promotion is set based on the actual annual subscriptions completed in the previous year. Newly registered groups start in the first year with the lowest discount level (10%), provided it can be credibly demonstrated that at least 10 annual subscriptions will be achieved with the group discount.

To activate a new group discount promotion for your club or association, the following steps are necessary:

1. The board of the club or association contacts us at and informs us that they want to start a group discount promotion.
2. We send the board of the club or association a list of promotion codes.
3. The board is then responsible for distributing the promotion codes to the members.
4. Each member can receive their personal promotion code from the board and redeem it themselves by following this guide.

A collective account for all members is not possible. Each club member needs their own subscription.

Of course not. It is also not allowed to post forecasts in private or public chat groups without prior permission or to systematically scrape forecasts via bots/scripts.

Just as you want to be paid for your work, we also want and need to be paid for our work on XC Therm. Think about it: In the long run, we can only create the best forecasts for you if we can finance our infrastructure and development.

We count on your fairness.

To find out whether the Regio subscription or the Pro subscription is sufficient for you, or whether you are better off with the Unlimited or Expert subscription, we recommend that you take a look at the overview map.

An overview of the number of regions per country is also provided by the following tables. Note that regions that are only partially located in a country are also counted as part of that country. Border regions have therefore been counted twice in these tables.

You should choose all regions at the beginning as adding regions later counts towards the 6 allowed changes.

Should you already have misunderstood this and you already used up your allowed changes, send us an email to . We will reset the counter of the allowed changes for you once.

The potential flight distance for each region is the distance in km that can be covered based on the thermal forecasts within a whole day. It is displayed on the overview map of the thermal forecast.

To calculate the potential flight distance, the following parameters are considered for each 30-minute interval:

Yes, the sink rate is already subtracted from the thermal climb rates. This means that you climb with the paraglider at the specified speed.

The primary focus of XC Therm and the underlying Regtherm model is on predicting thermal quality. Although wind values are also provided, since wind values are only available for a single grid point of the ICON model per region, this is far from sufficient for detailed flight planning in the mountains.

Example: The region Urner Alps extends from the Gotthard Pass to the Lake Lucerne, and from the Brünig Pass to the Klausen Pass. This corresponds to a radius of over 60 km. The grid point from which the wind values originate is approximately in the middle at the southern Lake Lucerne. While the region is drawn so that the thermal conditions are considered homogeneous, the wind values can vary greatly within the region.

For this reason, XC Therm also provides the high-resolution ICON-D2 wind and weather forecasts for free.

Yes, the thermal forecasts can be queried retrospectively up to December 6, 2012, for users with an active subscription in the archive. The last forecast for the respective day is displayed.

The archive data for the period 06.12.2012 - 31.12.2023 comes from the old regions (Alps and Central Europe). From 01.01.2024, the archive data comes from the new definitive regions (all of Europe).

However, the ICON-D2 forecasts cannot be queried retrospectively, as this involves enormous amounts of data.

Regtherm is not an independent weather model, but it takes the forecasts from numerical weather models as input data and calculates thermal-specific parameters such as climb rates and base heights. Until 2023, only input data from the ICON-EU weather model was used. From 2024, in addition to ICON-EU, the higher-resolution ICON-D2 will also be used.

First, the ICON-D2 model does not cover all of Europe, but only Central Europe. The following figure shows the regions where ICON-D2 data is available as input data for Regtherm.

Second, the ICON-D2 is only calculated for 2 days into the future. For forecast days 3-5, the input data from the ICON-EU model is used for all regions. The following table provides an overview of the input data for the Regtherm model.

In addition, the weather model on which a Regtherm forecast is based is always displayed in the detail view at the top right.

Previously, current measurements were also included in the Regtherm calculation. With today's high horizontal resolution of the input data, these measurements are already well enough considered in the weather models themselves and do not need to be integrated into Regtherm again. Therefore, real-time measurement data is no longer used as Regtherm input data.

The following tables provide information on the update times of the thermal forecasts. Since the calculation of Regtherm takes a few minutes, the following days are updated with a few minutes delay.

For the first two forecast days, the Regtherm model uses the ICON-D2 model as input data where available for the thermal forecast. The thermal forecasts are updated at the following times:

For all areas outside the ICON-D2 coverage and for forecast days 3, 4, and 5 of all areas, the Regtherm model uses the ICON-EU model as input data for the thermal forecast. The thermal forecasts are updated at the following times:

The division of the map into Regtherm regions is based on topographical features such as the course of mountain ranges, the height of valley floors, the volume of valleys, and the average height of the terrain.

This division based on topography is supported by scientific findings that show that convective mixing of the atmosphere mainly occurs along thermal circulation systems (slope wind, valley wind, alpine pumping). As a result, homogeneous atmospheric conditions are found in valleys on the one hand, and in regions with similar terrain height on the other.

In addition, the experience of local meteorologists and pilots regarding characteristic and recurring air mass boundaries can be useful in defining the regions more precisely. In your home flying region, you surely know such boundaries where the strength of the thermals and the base of the cumulus clouds often change significantly. For the creation of 1000+ new definitive regions, we have surveyed numerous local pilots across Europe.

Your feedback is also requested if you see potential for improvement in the delineation or naming of a region. If you think a region has been inappropriately delineated or you have a more suitable name, do not hesitate to contact us at . This helps us improve the forecast and the platform. It should be noted that we will take every feedback seriously, but we may not be able to address every concern and suggestion for improvement.

One might think that to get even more precise forecasts, smaller regions should simply be defined, down to the smallest valley in the Alps. This is not so simple, because the input models ICON-EU and ICON-D2 do not have the necessary grid resolution to capture such small-scale differences. If there is no air mass difference in the input data, the Regtherm forecast will hardly be able to depict a difference in thermal strength or cloud base. Therefore, the regions were only refined to the extent that the input model can still capture the topographical characteristics in its resolution. The new regions are thus as small as necessary to capture the characteristic air mass boundaries, and as large as possible to remain clear and user-friendly.

Example:

Ideally, we could define each small side valley as a thermal region so that the micro-meteorological processes are also modeled by Regtherm.

On the one hand, such a division with very small areas would lose clarity. For planning a longer flight, countless detailed forecasts would have to be viewed, and one would get lost in details. On the other hand, a fine-meshed division is of no use if the input model cannot sufficiently resolve the topography. The ICON-D2 can still "see" most valleys with its 2.2 km grid, but these are significantly flattened in the ICON-D2 topography.

When looking at the ICON-EU topography, it becomes clear that the input model has its limits and that only the coarser division makes sense. With the new regions, the landscape is divided into homogeneous regions, with the mountain ranges separating the main valley wind systems. The input model ICON-EU also "sees" these valleys and can thus capture potential air mass differences.

The old regions were originally developed for glider pilots and were too large to capture the air mass differences relevant to paragliding. The region Bernese Oberland extended, for example, from Rochers-de-Naye at Lake Geneva to Pilatus in Central Switzerland, a distance of 120 km. Every pilot knows that the thermal conditions and cloud base heights can vary greatly in such a large area.

With the new regions, Regtherm can now also capture air mass boundaries between larger valleys in the mountains and provide distinct thermal forecasts. The old region Bernese Oberland has now been divided into three new regions, namely Bernese Oberland, Bernese Alps, and Urner Alps. The new regions are as small as necessary to capture the characteristic air mass boundaries, and as large as possible to remain clear and user-friendly.

Until December 2023, XC Therm visualized exactly the same data as DWD Toptask, flugwetter.de, and Alptherm (AustroControl). This data came from the old regions of the Regtherm model and was produced by the German Weather Service DWD.

In March 2024, however, the German Weather Service discontinued its Regtherm production, and the aforementioned services were discontinued. Since January 2024, XC Therm has been providing the flying community with Regtherm forecasts.

Numerical weather models are rather generic models that should cover a wide range of weather phenomena. Many parameters important for a high-quality thermal forecast are not considered.

Regtherm, on the other hand, is a specialized thermal forecast. Regtherm is not an independent weather model but uses numerical models as input and calculates a forecast optimized for glider pilots and hang gliders using thermal-specific parameters. In technical jargon, this is also referred to as a post-processing procedure or downstream model.

More technical details about Regtherm are explained here.

For us paragliders and glider pilots, an accurate wind and weather forecast is crucial.

The ICON model family has proven to be very reliable for forecasting wind and convection in recent years. In addition to the German Weather Service DWD, the Federal Office of Meteorology and Climatology MeteoSwiss has also been using the ICON models since 2024.

At XC Therm, we want to offer the best wind and weather forecasts for all flying areas in Europe and especially in the Alps. The following ICON models are available at XC Therm:

The models ICON-EU and ICON-D2 from DWD (available for free even without a subscription).

The models ICON-CH2 and ICON-CH1 from MeteoSwiss (available from April 2025, only for XC Therm subscribers).

Here you can find all the important information about the models:

The ICON core is continuously developed by leading European weather services such as the German Weather Service DWD and the Swiss Federal Office of Meteorology and Climatology MeteoSwiss. More detailed information about the ICON model can be found here.

The resolution of a weather model is crucial for the quality of wind, temperature, and cloud forecasts. Especially in the Alps, where the topography is very complex, high-resolution models can better represent local conditions.

The horizontal resolution of a weather model indicates the size of the grid cells in which the model divides the atmosphere. The smaller the grid cells, the more accurately the model can represent the topographical conditions and thus the local phenomena. This, in turn, leads to more precise forecasts of wind, temperature, and clouds.

The vertical resolution of a model is defined by the number of model levels. The more model levels, the more accurately the model can represent the vertical structure of the atmosphere. This is particularly important for forecasting the wind profile and convection.

As paragliders and glider pilots, a precise wind forecast is particularly important to us, as we are confronted with small-scale wind phenomena such as valley winds, foehn, and lee winds in the mountains.

The forecast of foehn flows is a good example of the advantages of a high-resolution model. A high-resolution model can better represent the foehn flow and its channeling through valleys and passes, as the valleys are represented in their depth and structure in the model topography.

Another example is the forecast of convection. A high-resolution model can more accurately predict the location of strong updrafts and thus cloud formation, as it can more accurately simulate regional updraft sources and air mass boundaries.

However, even at a resolution of 1 km, there are still phenomena that the model cannot represent. An example is the forecast of thermals. The characteristic size of a thermal is 30 to 100 m, which is clearly below the resolution of a weather model. Therefore, we cannot expect a reliable thermal forecast from high-resolution weather models. For this reason, XC Therm offers thermal forecasts from the Regtherm model, which is specifically designed for thermal forecasting.

Since March 2025, all XC Therm subscribers can also use the high-resolution forecasts of the ICON-CH1 model. The ICON-CH1 model is currently the best model for forecasting wind and convection in the Alps.

Since March 2025, XC Therm has been offering high-resolution ICON-CH1 wind forecasts. For a test period, the forecasts can be used for free even without an XC Therm subscription.

During the spring, the ICON-CH1 forecasts will be expanded with cloud and precipitation forecasts, and the ICON-CH2 model will be integrated. With this combination, XC Therm will then offer the best wind and weather forecasts for the Alps. With 2 km resolution over 5 days and 1 km resolution for the following day, as well as wind forecasts at 14 different heights, you can better assess the wind and weather conditions in the Alps than ever before.

The ICON-CH1 and ICON-CH2 forecasts will be available only for XC Therm subscribers from April 2025. It does not matter whether you have a Regio, Pro, Unlimited, or Expert subscription: You can use the entire coverage of the models.

The ICON-D2 and ICON-EU forecasts will remain free even without a subscription.

The wind and weather forecasts are updated every 3 hours.

The exception is the high-resolution ICON-CH1 wind forecasts, which are currently updated only at 3 and 15 UTC daily.

The last update of the data is always visible at the bottom right of the status bar.

The atmosphere is divided into model levels in a weather model. These model levels are only parallel to the Earth's surface at high altitudes. Near the Earth's surface, they follow the terrain. Therefore, you cannot simply read the wind at a specific altitude.

The model data is interpolated to some pressure levels and then made available to the meteorological providers. Typically, these are the pressure levels 850 hPa (approx. 1458 m), 800 hPa (approx. 2000 m), 700 hPa (approx. 3013 m), and 500 hPa (approx. 5600 m). Most providers only show the wind values at these pressure levels, which is sufficient for normal use. However, this brings two problems:

1. The actual height of the pressure levels depends on the air pressure. In high pressure or low pressure, the deviation can be up to 150 meters up or down. Thus, the 3000 m forecast actually corresponds to a 2850 m - 3150 m forecast.
2. The pressure levels in the range of interest to hang gliders are too far apart. Thus, important altitudes such as 2500 and 3500 m are missing.

Some providers help themselves by interpolating the 800 hPa forecast from the weighted average of the 850 hPa and 700 hPa forecasts. This loses the actual vertical resolution of the weather model, as shown in the following image:

Other providers use model levels to calculate the 2500 m forecast and take the wind values from the nearest model level. This makes the matter significantly more accurate, as the model levels at 2500 m in the flatlands are only about 150 m apart.

XC Therm goes one step further: We download the weather model data with all model levels and use the same complex calculation (interpolation), as used by DWD and MeteoSwiss to calculate wind values to the exact meter. This allows us to offer highly detailed wind maps for any altitude above ground (AGL) and altitude above sea level (AMSL). The only limitation is the computing power of our servers.

On the map, you can choose between the wind forecasts of the ICON-CH model family (ICON-CH1 and ICON-CH2) and the ICON-DE model family (ICON-D2 and ICON-EU) in the upper menu. The model family is listed in the time selection bar at the bottom right, along with the time of the last forecast update.

Within a model family, you can differentiate between the higher-resolution model (ICON-CH1 or ICON-D2) and the lower-resolution model (ICON-CH2 or ICON-EU) as follows:

1. Time period: ICON-D2 and ICON-CH1 forecasts are available for a maximum of 48 hours. You can assume that the forecasts for the current and the following day come from the higher-resolution model. The forecasts for days 2-4 come from the lower-resolution model (ICON-CH2 or ICON-EU).
2. Arrow spacing: The arrows on the wind maps correspond exactly to the model resolution. In the ICON-CH model family, the arrows on a wind map are either 1 km apart (ICON-CH1) or 2 km apart (ICON-CH2). In the ICON-DE model family, the arrows are either approximately 2 km apart (ICON-D2) or around 6 km apart (ICON-EU).

XC Therm is exclusively tailored to the needs of paragliders, hang gliders, and rigid wings. Therefore, there is a wind scale specifically designed for the needs of these pilots for each category. For paragliders, flying in winds over 45 km/h is unrealistic, so higher wind values are not color-coded. This makes the wind maps clearer.

However, the exact wind values can always be viewed by tapping or clicking on the wind arrows.

Since the pressure differences refer to the air pressure at the ground, they provide little information about the conditions at the altitude of the Alpine passes, especially on days with inversions. Additionally, the temperature at altitude and the humidity also play a crucial role in whether foehn occurs. Therefore, pressure difference diagrams should be viewed with great caution and only as a rough indicator.

On the other hand, the wind forecasts of the high-resolution models (ICON-CH1, ICON-D2, ICON-CH2) take all the above parameters into account and can predict foehn flows much more reliably, especially at altitudes of 1500m, 2000m, and 2500m.