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The question “How humid will it be today?” is commonly pondered by people around the globe, as humidity affects everything from our hair to our energy levels. To measure humidity, forecasters often use relative humidity, which considers the amount of moisture 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. This is the temperature at which your sweat evaporates and you start to feel cool. Lower dew point temperatures feel dry, while higher dew points feel more humid.
Using this metric, the HouseFresh team previously identified the most humid cities worldwide. But they also wondered: where in the world do locals experience the driest air? To find out, the HouseFresh team used data from Weather Spark to count the number of “dry air days” (days with a dew point of 13°C (55°F) or below) that over 14,000 world cities and 5,000 U.S. cities experienced in 2023. Read on to explore the dry air capitals on every continent and around the world.
Table of Contents
- Key Findings
- The Dry Air Capitals of the United States
- Reno in Nevada: Leading the Nation in Dry Air Days
- The Dry Air Capitals of the World
- The Dry Air Capitals of North America
- The Dry Air Capitals of Europe
- The Dry Air Capitals of Oceania
- Dunedin Leads Oceania in Dry Air Days
- The Dry Air Capitals of South America
- The Dry Air Capitals of Africa
- The Dry Air Capitals of Asia
- Tips to Humidify a Room Without a Humidifier
- What Is Dry Air, and Why Does It Matter?
- Sources
Key Findings
- Reno, Nevada: Leads the U.S. with 363.91 dry air days annually.
- South America: Seven cities, including La Paz in Bolivia, experience a full 365 days of dry air per year.
- Europe: Reykjavík in Iceland tops the continent with 364.52 dry air days annually.
- Oceania: Dunedin in New Zealand has 352.51 dry air days annually, leading the region.
The Dry Air Capitals of the United States
Reno in Nevada: Leading the Nation in Dry Air Days
To discover which U.S. cities have the driest air, the HouseFresh team used the number of dry air days experienced in 2023. Reno, Nevada, topped the list with 363.91 dry air days annually, nearly a full year of uncomfortably dry air.
Close behind is Sparks, Nevada, with 363.78 dry air days annually. Both cities, located on the western edge of the Great Basin, are shielded from Pacific Ocean moisture by the Sierra Nevada mountains, creating a rain shadow effect.
The map above reveals the city in each state with the highest number of dry air days annually. Among the driest cities are Laramie, Wyoming, and Butte, Montana, both nearing 364 dry air days per year. In contrast, Mililani Town in Hawaii experiences just 11 dry air days annually, thanks to the cooling trade winds that make high humidity more comfortable.
The Dry Air Capitals of the World
Two South American Cities Experience Year-Round Dry Air
Mapping the city with the driest air in every country, two cities stand out with a full year of dry air in 2023: Cusco in Peru and La Paz in Bolivia. Both are near the Atacama Desert, one of the driest places on Earth.
Even typically humid countries have dry air hotspots. In the UK, Dundee experiences 344.9 dry air days annually and is Scotland’s sunniest city.
“It’s all about Scotland’s geography,” explains Grahame Madge of the Met Office. “Moist air from the Atlantic releases most of its rain in the western highlands, leaving the east coast, including Dundee, much drier.”
The Dry Air Capitals of North America
U.S. Dominates North America’s Dry Air Capitals
North America spans 23 countries, but over half of the continent’s top 10 cities for dry air are in the U.S. Reno leads with 363.91 dry air days annually, followed by Bend, Oregon (363.66), Boise, Idaho (361.22), and Anchorage, Alaska (360.93).
Outside the U.S., Calgary in Canada records 359.86 dry air days annually, its dryness attributed to the Rocky Mountains’ rain shadow effect.
The Dry Air Capitals of Europe
Reykjavík: Europe’s Driest Capital
Reykjavík, Iceland, experiences the most dry air days (364.52) in Europe annually. Despite its maritime climate, the city’s proximity to the Arctic Circle makes it vulnerable to cold, dry Arctic air masses.
Norway claims four of Europe’s top 10 driest cities, with Trondheim and Drammen each experiencing 351.99 dry air days annually. The cold, dry Arctic air influences these regions significantly.
The Dry Air Capitals of Oceania
Dunedin Leads Oceania in Dry Air Days
In Oceania, Dunedin, New Zealand, records 352.51 dry air days annually, the highest in the region. Dunedin, in the Otago region, receives less than 400 mm of rainfall annually. Christchurch follows with 327.64 dry air days.
Most of Oceania’s dry air capitals are in Australia, with Hobart leading at 346.60 dry air days annually. The city’s dryness is due to Mount Wellington’s moisture-sapping effect on prevailing winds. Other notable cities include Ballarat (345.29) and Adelaide (330.61).
The Dry Air Capitals of South America
Peru Dominates South America’s Dry Air Capitals
Peru claims five of the top 10 driest cities in South America, all experiencing a full year of dry air. Most of these cities are near the extremely arid Atacama Desert. Calama, Chile, experienced no rainfall between 1570 and 1971. Quito, Ecuador, close to the equator, has a consistently cool, dry climate with 364.65 dry air days annually.
The Dry Air Capitals of Africa
Aswan: Africa’s Driest City
In Africa, Aswan, Egypt, has the continent’s driest air, with 356.58 dry air days annually. Situated in southern Egypt, Aswan receives just 3 mm of rain per year.
Béchar, Algeria, with 353.18 dry air days, is among four Algerian cities in the top 10, all affected by the Sahara Desert’s arid climate. Addis Ababa, Ethiopia, the southernmost dry air capital, has 339.12 dry air days annually, its high altitude contributing to the dryness.
The Dry Air Capitals of Asia
Iran: Home to Asia’s Driest Cities
Asia, the largest continent, hosts diverse climates, yet all its top 10 driest cities are in Iran. Bīrjand leads with 364.77 dry air days annually, followed closely by Yazd and Shāhreẕā, each with 364.76 days. Iran’s arid and semi-arid climate, with minimal rainfall and cold winters, results in very dry air.
Tips to Humidify a Room Without a Humidifier
While we can’t control the outdoor climate, we can alleviate dry air indoors. Here are four tips to humidify your home without a humidifier:
- Air dry your laundry indoors: Hang clothes indoors to dry; the evaporating moisture will humidify your home.
- Leave the bathroom door open after showering: Let the steam circulate through your house to add moisture.
- Place water containers near heat sources: Position water containers on radiators or in direct sunlight to evaporate moisture into the air.
- Get houseplants: Plants like the Areca palm tree add moisture through transpiration, while also removing toxins from the air.
Dry air can cause various health issues and damage home fixtures. Recognize signs of dry air and use these tips to introduce moisture, improving comfort and protecting your home.
What Is Dry Air, and Why Does It Matter?
We often overlook the air around us, but it becomes noticeable when humidity levels are particularly high or low. Air feels dry when it’s either very hot or very cold. Cold air struggles to retain moisture, while hot climates cause rapid evaporation, leading to dry conditions.
Sources
The HouseFresh team gathered humidity data for large cities (with populations of at least 100,000) in every country and U.S. state from Weather Spark, covering 14,657 global cities and 5,175 U.S. cities. This data helped identify the driest cities based on the number of days with a dew point of 13°C (55°F) or below in 2023. The dew point more accurately represents how humid or dry a city feels compared to relative humidity.
For the U.S. state map, cities with populations of at least 25,000 were considered.
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