Dry air capitals: The cities with the driest air in the world

We counted the number of “dry air days" experienced in 2023 by people in over 14,000 global cities and 5,000 U.S. cities.
By
Published on June 24, 2024
Written by
Amparo Lopez
Amparo was a staff writer for HouseFresh for nearly two years. She is a sustainability advocate, holding degrees in communications, human-centered design and environmental policy. Her work has a focus on air pollution and climate change.

“How humid will it be today?” A common question for folks around the world to ponder as they plan their day since humidity can affect everything from our hair to our energy levels.

Forecasters measure humidity most commonly by looking at a day’s relative humidity, which considers the amount of moisture present in the air relative to the temperature.

However, the most reliable indicator of how dry or humid a day will feel is the dew point, the temperature at which your sweat evaporates and you begin to feel cool. Lower dew point temperatures feel dry, while higher dew point temperatures feel more humid. 

Using this metric, we previously identified the cities across the globe that feel the most humid. But we couldn’t help but wonder about those cities at the other end of the scale and ask: where in the world do locals live with uncomfortably dry air the most?

To find out, we used Weather Spark data to count the number of “dry air days” (days that had a dew point of 13°C (55°F) or below) that over 14,000 global cities and 5,000 U.S. cities experienced in 2023. Read on to discover the dry air capitals in the U.S., on every continent and across the globe. 

Key findings

  • Reno in Nevada experiences more dry air days (363.91) per year than any other U.S. city.
  • In South America, seven cities (including La Paz in Bolivia) count a full 365 days of dry air per year.  
  • In Europe, Reykjavík in Iceland has the driest air on the continent (364.52 annual dry air days), but Norway claims another four of the top 10
  • In Oceania, Australian cities dominate our top 10 dry air ranking — but Dunedin in New Zealand counts the most dry air days of all (352.51)

The dry air capitals of the United States

Reno in Nevada has more dry air days per year than any other U.S. city

We first wanted to find out which cities in the U.S. have the driest air using the number of dry air days they experienced in 2023 as a proxy. Reno in Nevada comes top overall with 363.91 dry air days per year, a count just two days short of a full year of uncomfortably dry air. 

After that comes Sparks, a city just a stone’s throw from Reno, which counts 363.78 dry air days annually. Situated on the western edge of the Great Basin, both cities are blocked from the moisture of the Pacific Ocean to the east by the Sierra Nevada mountains, an effect known as a rain shadow.

Our map above reveals the city in every state with the highest count of dry air days per year. Among the country’s driest cities are Laramie in Wyoming and Butte in Montana, both of which count close to a full year (364 days) of dry air. In contrast, Mililani Town in Hawaii only experiences 11 dry air days per year. High humidity tends to be comfortable in Hawaii due to the cooling effect of the state’s trade winds.

The dry air capitals of the world

Two South American cities experience a full 365 days of dry air

Next, we mapped the city in every country with the driest air of all. Two cities on the map stand out as having experienced a full year of dry air in 2023 — Cusco in Peru and La Paz in Bolivia. Both of these cities are situated on the cusp of the Atacama Desert, one of the driest regions on the planet. 

Even countries we might typically think of as more humid have their own dry air hotspots. In the UK, for example, Dundee experiences 344.9 dry air days per year. It’s also the sunniest city in Scotland. 

“It is all down to the geography of Scotland,” explains Grahame Madge, a spokesman for the Met Office. “Most of the weather comes in from the Atlantic, with moist air being forced up toward the western highlands … a lot of the rain is released in the western regions, by the time the air makes its way over to the lower regions of the east coast, it is drier. Dundee is also sheltered by the Cairngorms and other high regions, meaning that it is generally warmer.”

The dry air capitals of North America

The U.S. claims more than half of North America’s top 10 cities for dry air

While North America spans 23 countries from the polar reaches of Canada to Cocos Island in Costa Rica, over half of the top 10 cities on the continent with the driest air can be found in the U.S. Reno leads with 363.91 dry air days per year. But Bend, Oregon (363.66 annual dry air days), Boise, Idaho (361.22 annual dry air days), and Anchorage, Alaska (360.93 annual dry air days), also feature. 

Outside of the U.S., Calgary in Canada ranks with a count of 359.86 dry air days per year. Calgary is blocked from the moisture of the Pacific Ocean thanks to a rain shadow created by the Rocky Mountains.

The dry air capitals of Europe

Iceland’s capital city Reykjavík has the driest air of any European country

Turning our attention to Europe, we found that Reykjavík in Iceland experiences more dry air days (364.52) per year than any other city on the continent. Thanks to the effects of the Gulf Stream, Iceland has a mild maritime climate, but being so close to the Arctic Circle, it’s also vulnerable to very cold and dry Arctic air masses.

Meanwhile, Norway claims another four of the cities in Europe with the driest air. Leading the pack are Trondheim and Drammen, both of which experience 351.99 dry air days per year. Like Iceland, Norway is vulnerable to cold, dry Arctic air because of cold air’s reduced capacity to hold onto moisture. “In some places, Arctic air is as dry as air in the Sahara Desert,” comments the National Snow and Ice Data Center.

The dry air capitals of Oceania

Dunedin in New Zealand experiences more dry air days annually than any other city in Oceania

In Oceania, Dunedin in New Zealand counts more dry air days (352.51) per year than any other country. Dunedin is the principal city of the Otago region, of which the Central Otago district is the driest of any in the country, receiving less than 400 mm of rainfall a year. The next city in New Zealand featured in our ranking is Christchurch, which sees 327.64 dry air days annually. 

But most of the dry air capitals of Oceania are in Australia. Hobart leads the pack, a Tasmanian city where locals experience 346.60 dry air days a year. The air is dry here because the neighboring Mount Wellington saps the moisture from the prevailing winds before it can descend into the city. Ballarat (345.29 dry air days a year) and Adelaide (330.61 dry air days a year) on the mainland come next. 

The dry air capitals of South America

Peru claims five of the top 10 dry air capitals in South America

South America is a stand-out continent when it comes to dry air: seven cities (five of them in Peru) counted a full 365 days of dry air in 2023, with the remaining three experiencing just over 364 days.

Most are either in or on the edge of the Atacama Desert, an extremely arid region thanks to the cold Pacific Ocean’s moisture-sapping effects on the air. So dry is the Atacama Desert that Calama (364.67 dry air days a year) in Chile experienced no rainfall at all between 1570 and 1971. Meanwhile, Quito (364.65 annual dry air days) is the only South American dry air capital to be found in Ecuador. The city is situated close to the earth’s equator, lending it a consistently cool climate. 

The dry air capitals of Africa

Aswan in Egypt counts more dry air days per year than any other African city

Over in Africa, Aswan in Egypt takes the title of having the driest air of any city on the continent, counting 356.58 days of dry air in 2023. Situated in the south of Egypt, Aswan is one of the world’s driest cities, receiving only 3 mm of rain a year.

After Aswan comes Béchar — one of four Algerian cities in our ranking — with a count of 353.18 annual dry air days. It’s no wonder the air in Algeria is so dry, as the Sahara desert spans nearly all of the country’s territory. The furthest south of the continent’s dry air capitals is Addis Ababa, Ethiopia’s capital and largest city (339.12 annual dry air days). At 7,726 ft above sea level, the air here is thinner and less capable of holding moisture than a city at a lower altitude. 

The dry air capitals of Asia

All of Asia’s dry air capitals are in Iran, led by Bīrjand in the east of the country

As the biggest continent on the planet, almost every known climate occurs somewhere in Asia. Despite that, all ten of its dry air capitals can be found in just one country: Iran

Bīrjand comes out on top with 364.77 dry air days a year, followed by Yazd and Shāhreẕā, both of which count 364.76 annual dry days. Most of Iran has an arid or semi-arid climate, experiencing little rainfall and, as a result, water supply shortages. The winters can also be very cold here, a weather condition that causes dry air thanks to cold air’s inability to hold onto moisture well. 

Four ways to humidify a room without a humidifier

While we can’t control the outdoor climate and weather where we live, we can alleviate the problem of dry air in our own homes. Humidifiers are a great solution, but if you can’t get one, here are some things you can do to tackle the problem of dry air indoors. 

  1. Air dry your laundry inside. Instead of throwing your clothes in the dryer, hang them up indoors on a clothes horse or something similar. Not only are you saving on energy bills, but as the clothes dry, the moisture evaporates into the air and humidifies your home. 
  2. Leave the door open after showering. Once you’ve finished having a shower, don’t let all that steam go to waste: open your bathroom door so the moisture in the air can circulate through your house. 
  3. Place a container of water near a source of heat. Fill a container with water and leave it on a radiator or in direct sunlight so that the water evaporates into the air. 
  4. Get a houseplant. Some houseplants add moisture to the air through a process called transpiration. Previously, we found that the best you can buy is an Areca palm tree, which humidifies your air while removing chemical toxins.

As we’ve explored, dry air can trigger a range of health conditions and impact the health of your home’s fixtures and furnishings, too. Introducing more moisture to indoor air by investing in a humidifier or using these tips can relieve uncomfortable physical symptoms and protect your home from damage.

Here’s how you can tell if the air in your home is particularly dry and just some of the ways it can affect someone’s health.

SOURCES

We began our research by retrieving humidity data for large cities (with a population of at least 100k) in every country and U.S. state from Weather Spark. This gave us data for a total of 14,657 global cities and 5,175 U.S. cities. 

This enabled us to identify the top cities by country, by continent and in the U.S. with the driest air based on the number of days in 2023 they had a dew point of 13°C (55°F) or below. The dew point defines humidity comfort levels. Lower dew point temperatures feel drier, and higher dew points feel more humid. The dew point better represents how humid a city feels than relative humidity. This is explained here and here.

For our U.S. state map, we lowered the threshold to consider cities with a population of at least 25k. 

Join our newsletter

We’ll send you a nice email every once in a while. No spam.

Support HouseFresh

Buy us a coffee
Your support makes it possible for us to keep doing what de wo.
About the author

Amparo Lopez

Amparo was a staff writer for HouseFresh for nearly two years. She is a sustainability advocate, holding degrees in communications, human-centered design and environmental policy. Her work has a focus on air pollution and climate change.

Join our newsletter

We’ll send you a nice email every once in a while. No spam.

Support HouseFresh

Buy us a coffee
Your support makes it possible for us to keep doing what we do.
We are ad-free and buy all the devices we test with our own money. When you buy through links on our site, we may earn an affiliate commission, which we use to fund new product tests. Learn more