Cold-weather limits in cross-country skiing – is -20°C too cold?
Shortened version published as a guest column on November 18th 2025 at hiihtokokki.fi
The first races of the early season have been skied in the North. I spent ten days with Team Electrofit: we tested plenty of skis, gave flu vaccinations, and the speed looked promising heading toward Ruka.
In Sunday’s races in Olos, the weather was a bit brisker, about –10 to –12 °C, even though it was –25 °C down in the village of Muonio, thanks to an inversion caused by the fell weather. This phenomenon is familiar to many who spend time outdoors in the North, and there was no need to fear that the race would be cancelled or that the skiers’ safety would be at risk.
Cross-country skiing, Nordic combined, and biathlon are exceptional Olympic sports. Before ski mountaineering joins the Olympics next winter, they have been the only endurance sports in which competitions are held clearly below freezing. Cold air is part of the nature of the sport, but somewhere there is a threshold where the health risk may become greater than the athletic benefit. At the moment, FIS competition rules state that a race can be held if the coldest point on the course is –20 °C or warmer. Wind conditions must also be taken into account.
Cold affects the whole body during exercise, and the topic is very broad. In this text, I focus on how cold air affects the airways during competition.
What does cold do to the airways?
In high-intensity endurance exercise, the lungs ventilate 100–200 litres per minute. In freezing conditions, the inhaled air is very cold and dry. When cold and dry air flows quickly through the airways, it cools the mucous membranes, dries out the airways, and loads the bronchi both mechanically and chemically.
In the long term, this may increase the risk of developing asthma. A clear causal relationship has not, however, been established, but we do know well that especially cross-country skiers have more asthma than the general population. It would appear that asthma does not develop in a single race, but even a single bout of intense exertion in cold air can irritate the airways for several days.
What do skiers themselves think about cold-weather limits?
As part of my PhD project, we conducted a survey on the respiratory health of Finnish cross-country skiers in spring 2019. As a small but interesting part of the questionnaire, we also asked athletes’ own opinions about temperature limits for competition. The results were published in summary form on the hengitystutkimus.fi website. (link)
What did we find? (351 respondents)
66% of skiers said they always compete if the race is held.
When we looked at athletes over 16 years of age (for whom the FIS -20 °C limit practically applies), only 13% considered -20 °C or colder to be an appropriate temperature limit.
On average, the temperature limits considered appropriate were:
-16.8 °C for those over 16
-15.1 °C for those under 16
In other words, most athletes would prefer a warmer limit than the current -20 °C. In my view, this is an important message. Athletes understand that cold is part of the sport, but they do not want to compete at any cost.
After the survey but before the results were published, the Finnish Ski Association had already raised the temperature limit in Finland to –15 °C, which essentially corresponds to the average opinion among young skiers. In the Scandinavia Cup for adults, a stricter –17 °C limit has been used since the 2016–2017 season, and this has been applied several times since.
Sprint, distance, and long races – should the limits differ?
Two perspectives have come up in discussions with athletes and colleagues:
Sprint races in severe cold feel harsher on the airways for many athletes, because skiing speed and intensity are at or even above maximal oxygen uptake, and for those who reach the final this is repeated four times in a day.
Distance and long races involve a longer exposure, and although the speed is not as high, the total duration of exposure is very long and the exposure of the rest of the body must also be considered.
The combination of duration and intensity determines both the load on the airways and the risk of frostbite. The current single -20 °C limit for all competition formats does not take this into account.
Personally, I think it would be reasonable to consider warmer limits in sprint races. In long-distance races (e.g. 50 km and mass-start long-distance events), special attention should be paid to frostbite and hypothermia risk (for example fingers, toes, face, genitals).
Why isn’t there research to define the “right” temperature limit?
Let’s imagine we make skiers ski hard at different sub-zero temperatures, measure body temperature, inflammatory markers, lung function, and then conclude that “from this temperature down, competition is not allowed”.
In practice, such a study would be almost impossible ethically. Participants cannot be deliberately exposed to conditions that are expected to cause mucosal damage or frostbite. The risk of severe frostbite injuries is not acceptable, even if the participants volunteer. Ethics committees would likely not approve study designs where the harm is so clearly foreseeable.
Another option in scientific terms would be opportunistic research: go to races that are already being held in very cold conditions and perform measurements before the start, during the race with wearable sensors, and immediately at the finish (e.g. spirometry, blood biomarkers, body temperature).
This could be challenging in practice but would be possible with good resources. It would be a burden on the athletes, and for example, several spirometers would be needed at the finish. In addition, the variables measured are often quite noisy and variable, so differences between temperatures might not be detectable in individual races.
Breathing masks and protecting the lungs
One way to protect the airways in cold is to use heat-exchanger masks (Airtrim, Jonasmask, etc.). In a Swedish study, it was observed that in a 4-minute maximal effort while skiing (similar to a sprint prologue) at -15 °C, lung function did not deteriorate after the effort when a breathing mask was used, compared with skiing without a mask.
Even with a good mask, breathing is harder work, and in a long race the accumulation of moisture and its freezing increases breathing resistance. For this reason, not all athletes like the feeling of a mask or feel that it interferes with breathing. Nonetheless, I strongly recommend trying masks in cold conditions.
Figure. Julia Kern (bib 55) wearing an Airtrim mask on the final day of the Ruka World Cup in 2019, where she finished 55th. Since then, she has won silver and bronze in the team sprint at the World Championships.
Frostbite risk
In discussions about cold-weather limits, we cannot ignore peripheral circulation and frostbite injuries. In cold weather, for example at -20 °C, the risk of frostbite is on a completely different level than at -10 °C, especially if it is windy. In Ski Classics races, we have seen severe frostbite injuries and even amputations.
When it comes to preventing frostbite injuries, individual athletes’ choices are not enough. Even if an athlete wants to compete at any cost, organizers and rules are responsible for ensuring that no one is exposed to an unreasonable risk.
My proposal
Combining the load on the airways, frostbite risks, and athletes’ own views on cold-weather limits, I would propose the following rule changes:
For seniors, -17 °C would be a better-justified general limit than the current -20 °C. This is already in use in the Scandinavia Cup.
For juniors under 16, -15 °C is an appropriate limit and is already used in Finland.
In long races (e.g. 50 km and mass-participation long-distance races), not only temperature but also the effect of wind should be carefully assessed.
The purpose of the rules is not to turn skiing into an indoor sport; cold is part of the nature of the discipline. However, rules can help ensure that the responsibility for deciding whether it is safe to start does not rest solely on the individual athlete in conditions that may be harmful to health. Athletes’ health and safety can be better protected than at present, without cross-country skiing losing its character as a winter sport.
Rikhard