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WEATHER

Why are temperatures of 25C considered a heatwave in Sweden?

In other parts of the world, 25C (77F) is an average summer’s day, so why do Swedes feel the heat more, and what can be done to mitigate the effect of heatwaves in the future?

Why are temperatures of 25C considered a heatwave in Sweden?
Children, the elderly and people with underlying health conditions are more likely to react badly to the heat. Photo: Martina Holmberg/TT

Sweden’s meteorological institute SMHI has issued heatwave warnings for this week, bringing with it a fire risk as temperatures are expected to hit 25-30 degrees Celsius across much of the country.

For readers from a lot of other countries, this might not feel like a big deal, but in Sweden, it’s warm.

There is no standard international definition of a heatwave, with each country deciding how to define it.

In Sweden, the national meteorological institute SMHI defines “high temperatures” as a maximum of 26C three days in a row and “very high temperatures” as a maximum of 30C three days in a row.

If temperatures hit 30C for five days in a row, or reach 33C for three days in a row, this qualifies as “very high temperatures”.

“Extreme heat is a new problem in Sweden,” Martina Söderström, from engineering consultancy company Sweco, told The Local. “It’s only really become an issue in the last ten years, with 2018 a bit of a wake-up call, with very high temperatures and a long heatwave.”

Summer 2018 saw a record number of wildfires ravage the country, Sweden’s hottest July in over 250 years, and the warmest summer since records began across most of southern and central Sweden.

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Not only are Swedes in general more used to cold temperatures, but the country’s infrastructure is built with cold temperatures in mind.

“It’s how we’ve built our buildings and our society. Buildings aren’t designed to protect people from heat and sunlight, rather they are designed to be insulated,” Söderström said.

Swedish buildings are also unlikely to feature ceiling fans or air conditioning, which, coupled with the fact that many of them are well-insulated, means that it can be difficult to cool them down once they’re already hot.

‘Natural solutions are an important piece of the puzzle’

Sweco recently investigated how a number of different European cities, including Stockholm, could build heatwave resilience as climate change looks likely to increase their frequency. In Stockholm, the number of heatwave days per year is expected to increase by 150 percent by 2100, with similar figures for the other Scandinavian capitals Copenhagen (160 percent) and Oslo (140 percent).

“The increase in temperature is greater here [in the Nordic countries] and we have probably come the least far in planning for it. We’ve been more focused on protecting ourselves from the cold,” Söderström said. “If you look at Rotterdam and Brussels, for example, they’re further ahead both in measuring the heat and maybe also have a clearer plan of the measures they’re going to take to mitigate it.”

Sweden also has a lot of sunlight during the summer – Stockholm gets over 18.5 hours of sunshine around midsummer, Malmö in the south gets 17.5 hours, while in the far north of the country the sun doesn’t set for months. This means that temperatures often stay high during the night, providing fewer opportunities for people to recuperate from the heat and putting more stress on vulnerable individuals.

Cities are not designed with heat in mind, either, meaning that they often lack shade or trees, which contribute towards keeping temperatures low.

“Natural solutions are an important piece of the puzzle,” Söderström said.

“It’s important to get green and blue infrastructure into city planning. Trees are great, as they give shade and also they release water vapour into the air which has a cooling effect, and bodies of water can have the same cooling effect – when it’s cooler than the surrounding air, it helps to cool it down. So water, green solutions, proximity to parks and shade, all of those things are important to have in a city environment.”

People in cities are also more affected by heatwaves, Söderström added, as hard surfaces like asphalt, concrete and metal roofs absorb heat, further warming the air as this heat is emitted.

“It’s important to think about this when planning areas. Think about getting plants and water into urban areas, but also the materials being used.”

Sweden can learn a lot from hotter countries

Sweden has “a lot to learn” from countries which are used to warmer temperatures already, she added, saying that there’s no need to “reinvent the wheel”.

“Things like how to plan buildings and cities, lighter materials, how to place buildings to allow the wind to move through them, building covered verandas, providing shade, for example.”

Although children, the elderly and people with underlying health conditions are more susceptible to high temperatures, they are by no means the only groups to feel the consequences of prolonged heatwaves.

“These types of temperatures put stress on all aspects of society,” Söderström said. “It’s not just individuals who are particularly sensitive to heat, but it has consequences for the entire population. It affects agriculture, forestry and our ability to secure a steady supply of water.”

“We need to start thinking about how to protect society [against heatwaves] and plan ahead. Measure, get an idea of where risk areas are or how they come about, and make a long-term plan for them,” she added.

“It’s time to act now. This is going to continue for at least another eighty years and if we act now, we can adapt so our society and our cities are more resilient in the future.”

Do you come from somewhere with a warmer climate than Sweden? How do you find the heat here? Does it affect you more or less than it did back home? Let us know in the comments below.

Member comments

  1. I come from southern part of India from Karnataka state. My hometown Udupi which is coastal and has a long costaline goes upto 38-39 during peak summers. The heat in Sweden at 24-25 celcius feels the same as our summer of 38-39 degree celcius. I think intensity of sub rays here is very high when compared to my hometown or in general in India. My hometown is also very humid throughout the year which makes you feel like just scratch off your skin from your body.

  2. I moved here from Austin TX, and the summer temperatures here are a welcome relief! Air conditioning is ubiquitous in Texas, but you’re barely able to function outside so you can’t really enjoy it.

  3. I come from South Africa and how different the same temperatures in Sweden and SA are.
    e.g. 25 degrees in SA is very pleasant but here I feel like I’m boiling!
    30 degrees there is hot but OMG here I wouldn’t go outside, unless is was to jump into a pool, because it feels like I’m being ironed alive by the sun!
    In SA in the summer the hottest time of the day is between 11am and about 2pm.
    Here it feels like 5 or 6pm is the hottest time of the day.
    It’s insane!
    Wonder if it’s because one country is way North and the other is way South.
    Or one country’s closer to the sun? 😉

  4. I am also from South Africa and believe me the Swedish summer heat is really hot. I agree with Belinda in a previous comment that 25 degrees in SA is very pleasant. Maybe it’s all the water around us here? Or our angle on the curve of the earth? The dry Joburg summer heat of which can reach a daily temp of 35 degrees is more manageable than today’s temp here in Sweden!

  5. I use a humidifier filled with ice water, and a fan to blow cooler air into my apartment. From 13:30 till sunset it’s very warm on the sunny side of my garden. I pull down the shades which don’t allow the sun to shine through, and curtains to lock the heat in between. It’s really quite comfortable inside my apartment living room, Outside it maybe 26C but inside it’s a cool 12C.

  6. I come from the Midwestern and Southwestern US. There they have various techniques to protect from both the heat and the cold. My personal favorite was in New Mexico where they range from 40° in the summer to -10° in the winter. Adobe is an excellent building material where the natural environment is mostly dry. Basically clay, it retains the heat in the 45 cm thick walls and allow it to slowly release during the nighttime. This could work in the middle areas of Sweden. It even scales up, with buildings up to five stories using it. Doesn’t work for skyscrapers, though.

    For the wetter areas, brick is a better option. Since bricks are also made from clay, they have many of the same properties. Covering them with vinyl siding, however negates the heat-resistant properties. Which means that people could have appliqué siding for the colder months. Like winter/summer tires. Just remove the siding for the heat and replace it for the cold. Of course, these building techniques mostly work in areas with large clay beds. Which Sweden doesn’t have. Sigh.

  7. It’s really fascinating reading all of these comments, thank you all for sharing! What techniques do your native countries apply to protect people and cities during heatwaves, and could any of these work in Sweden?

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LIVING IN SWEDEN

Which Swedish cities are most popular among young professionals?

A new study from Stockholm-based research company Future Place Leadership listed Gothenburg as the most attractive Swedish city to live and work in.

Which Swedish cities are most popular among young professionals?

The Talent City Index study measured the attractiveness of 75 different Swedish cities on a number of different metrics, like innovation and creativity, how family friendly they are, how beautiful they are and how attractive they are as places to start a company.

Unsprisingly, the country’s three largest cities were all in the top three.

The most attractive city on the list was Gothenburg, with 31.1 percent of respondents ranking it as one of their top three choices. Stockholm came in just 0.1 percentage point lower than Gothenburg, on 31 percent, with Malmö coming in third on 15.2 percent.

Rounding out the top five was Gotland on 13 percent followed by Helsingborg on 10.7 percent.

They also asked workers in sectors where there is a labour shortage, like IT specialists, teachers, healthcare workers and engineers, where they would prefer to live. This was bad news for Norrland, which is in dire need of skilled workers in the near future.

The most attractive region in Norrland was Umeå, in 16th place, followed by Gävle in 18th place and Luleå on 25th place. Next up were Sundsvall, Östersund/Åre and Boden, on 30th, 33rd and 37th place, with Skellefteå, the home of battery factory Northvolt, placing 39th. Örnsköldsvik and Höga Kusten came in at 40th place.

The county with the most cities in the top ten was Skåne, with Malmö, Helsingborg and Lund all placing highly.

When asked to rank regions individually, however, Stockholm region came in highest with 44.3 percent, followed by Västra Götaland on 29.2 and Skåne close behind on 29 percent.

Do you agree with this ranking? Where in Sweden do you live and would you recommend it to young professionals?

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