It is a crisp winter morning in the Finnish coastal city of Oulu, the fourth most northerly city in the world, just 100km south of the Arctic Circle. Last night there was a snowstorm and today the temperature hovers at about -5C (23F), but that is not deterring the city's hardy cyclists. Everywhere you go, people of all ages flurry by over the fresh snow, wrapped in winter clothes and seemingly enjoying the brief pale sunshine and bitingly cold air. 

Oulu, which proudly calls itself 'the winter cycling capital of the world' is blanketed in snow for five months of the year. During the depths of winter, temperatures can drop as low as -30C (-22F), with just four hours of daylight.

Despite these harsh conditions, 12% of winter journeys are made by bicycle in the city of Oulu. Compare that with the milder climate of England, where year-round the proportion of trips made by bike is a mere 2%.

So how did Oulu gain its reputation for keeping cyclists on the move even in the depths of winter?

When the Sun is shining and the snow reflects the light it's a lovely environment. Sometimes I even take the longer route across the frozen sea – Harri Vaarala

At first sight, the beautiful wintry surroundings look like they have something to do with it.

"I cycle 27km every day to work, and when the sun is shining and the snow reflects the light it's a lovely environment," says Harri Vaarala, a traffic engineer for the city of Oulu, who is responsible for promoting the benefits of cycling to its residents. "Sometimes I even take the longer route across the frozen sea. One time I realised I was late for a team meeting, so I stopped and joined it virtually in the middle of the frozen sea."

But without proper cycling infrastructure, the attraction could soon wear off. The city has also made a long-term commitment and investment in cycling, as part of the city's push towards sustainability and lowering car emissions, says Vaarala. 

Paths for people using bicycles, mobility scooters or travelling on foot are cleared of snow as a priority in Oulu before roads. Image: City of Oulu. 

The city encourages cycling by clearing the paths every day during the winter, using a fleet of heavy-duty snow ploughs. One of the most impactful changes is also one of the simplest: clear the roads of snow only when the cycle paths are done.

"Three to four centimetres of fresh snow is no issue for cars, but it might be a problem for cyclists and prevent elderly people from going outside at all," says Vaarala. The cleared cycle paths also provides access around the city for people who use mobility scooters.

"The trick is that it doesn't cost a penny more, we use the same personnel and equipment as we use for the roads, it's just a question of the order in which we do it," says Vaarala. 

The teams in charge of maintaining the cycle paths also have to use the paths themselves, so they experience first-hand the difference a well-maintained route can make. They also arrange 'roadside events' with hot drinks to get feedback from cyclists.

"It's also about how we communicate to our residents," says Vaarala. "When there's a major snowstorm some other places might say, ';eave your bike at home and take a bus or car.' We've decided in the city of Oulu to never send that kind of message. Instead, we say, 'there's a major snowstorm coming, please leave your car at home and take a bicycle because the paths will be cleared by 7am'."

The popular choice

Elina Tähtelä, a 31-year-old freelance dancer and choreographer, cycles to daycare and then on to work each day with her two children, four and two years old, riding in a little trailer attached to her bike. She says it is the fastest and most reliable way to travel.

"You can see it's protected and cosy in [the trailer], and cycling is also a great warm-up for me," says Tähtelä. "I wear glasses when it's snowing and a long coat and trousers to protect against the wind, and if you don't stop you don't get too cold."

Tucked up in their trailer, her children wear the same warm clothes as they do to the playground, school and around town, says Tähtelä. 

Clear signage projected onto the groomed paths helps keep them safe for bicycles and pedestrians alike. Image: City of Oulu. 

Tähtelä's family are in good company. In one of Oulu's biggest schools Metsokangas, more than 90% of the children get to school by bike or on foot, according to the school's headteacher, even during the coldest winter months. One reason is that traffic calming measures mean there is only one way to get to the school by car with no shortcuts, but there are multiple routes by bike.

Across all of Oulu's schools, an average of 50% of children make the trip by bike, which is the highest in Finland.

"I don't think kids aged seven cycle to school alone in many other countries," says Vaarala, adding his four-year-old son loves cycling in the snow. "It's part of our history and our way of life and they grow up with it, so you don't hear kids complaining about it."

Continues to expand its cycling network

In Oulu, the cycling heritage goes back a long way as the network of cycle paths was first planned to sit alongside the roads by city planners in the 1960s. Since its inception, the network has grown extensively, and has more than 900km of pedestrian and cycle paths combined. And Oulu continues to expand its cycling network.

Switching to cycling can help reduce emissions from transport far more quickly than replacing internal combustion engine cars with electric vehicles. One study in European cities found that switching to cycling or using an e-bike just one day a week can reduce a typical city resident's carbon emissions from transport by half a tonne of CO2 a year, the equivalent of a round-trip flight from London to Rome. Cutting transport emissions will be a key part of Finland's national plan to reach net zero by 2035.

The Oulu model has been used as a case study for other northerly cities hoping to embrace winter cycling. In 2013, the Winter Cycling Federation was founded in Oulu to promote winter cycling internationally, and has since held conferences in cities around the world.

I think in Oulu, cycling is a state of mind – Claes Kruger

One key challenge for winter cycling is safety. Oulu uses several interventions to address this. The paths are well lit during the dark winter months, and there are 320 underpasses so that children, in particular, don't have to cross roads, notes Vaarala.

There is also a system of projector-based signs that are illuminated from lamp posts onto the snowy surfaces. Residents of Oulu were among the most satisfied in Finland with safety of city transport, including cycling infrastructure, according to a national survey. 

The small city of Oulu is surrounded by nature, with cycle paths connecting the city to the countryside beyond. Image: City of Oulu. 

The city is now in the process of widening the cycle paths from 3.5m to 6.6m to build cycling 'superhighways' for cyclists and pedestrians.

The health effect

Claes Kruger, 47, is a development manager for the city, and is one resident who has made the shift from four wheels to two.

"After a day of hard work, it's a great way to clear the mind, it's good exercise and it's relaxing," says Kruger. "I cycle in all weather, I've cycled in -25C, in snowstorms, and I don't have winter tyres on my bike because they grit the paths. Cycling is in our culture. I think in Oulu, cycling is a state of mind."

The mental and physical health benefits are another reason for the city's cycling push, says Vaarala. "We also want to make sure that all the citizens are able to go outside during the winter months," he says. "We do believe it keeps them healthier, happier and more active."

It is well known that cycling benefits our mental health, fitness and cardiovascular health as well as reducing our risk of diabetes and cancer. In Europe, encouraging healthy levels of physical activity could prevent 10,000 premature deaths a year.

In high-latitude regions like Oulu, winter cycling has the added advantage of increasing exposure to sunlight and vitamin D when the days are short. A study of more than 5,700 Finns found that physical activity was one factor linked to higher vitamin D serum levels, alongside others such as a healthy BMI, not smoking and a healthy diet. And though many are less active in the winter months, exercising in cold temperatures has particular benefits for health and mental health.

Wherever you go in Oulu, whose urban region is home to 250,000 citizens, nature is never far away. Many of the city's cycle paths go through parks or by the sea. Many Finns have pointed out that even though the temperatures can dip very low, it is a dry cold, which is easier to cope with than a wet, humid cold.

When I get on a bike to try some winter cycling myself, I notice that the snow on the ground and in the trees lends a lovely peace and quiet to the whole experience. As long as you're wearing thermals and gloves. 

Author: Laurel Ives. This article first appeared on the BBC website Future Planet.