Lima, Peru’s capital city with over 10 million residents, lies uniquely between towering Andes mountains and the vast Pacific Ocean. Known for its rare tropical desert climate, Lima surprises with mild temperatures, persistent fog, and almost no rain. Discover why Lima’s climate is unlike any other city in the world.
Lima’s Origins and Tropical Location
Founded in 1535 during the Spanish conquest, Lima is Peru’s capital and sits at just 12°S latitude, placing it deep within the tropics. It spans the Pacific coast, enclosing a population exceeding 10 million in its metropolitan area. Despite its tropical position, the city receives virtually no rain, a stark contrast to other tropical metropolises. Lima instead experiences persistent high humidity, frequent low clouds and fog, and extremely dry weather overall.
Why Tropical Deserts Are Rare—and Why Lima Is One
Most deserts around the world belong to one of two categories: hot subtropical deserts, found just outside the tropics (beyond 23° latitude), and cold deserts, found inland or in mountain rain shadows. Tropical deserts—especially major urban ones—are nearly unheard of. Lima defies these norms thanks to two key factors: the Andes mountains and the Humboldt Current.
The Andes: Blocking the Rainy Season
To the city’s east, the Andes soar above 6,300 m (20,000 ft), acting as a natural barrier to moist trade winds arriving from the equatorial Pacific during the summer. Without them, Lima would experience a classic tropical savannah pattern: a defined wet season followed by a dry one. Instead, the Andes block that moisture entirely, leaving the city dry year-round.
The Humboldt Current: Cooling the Tropics
Parallel to the coast flows the cold Humboldt (or Peru) Current, which brings frigid waters from the mid-latitudes toward the equator. Near Ecuadorian borders, water temperatures hover around 16 °C, roughly 10 °C cooler than expected for a tropical latitude. This dramatically cools the air above the ocean, which shapes Lima’s unusual climate.
Mild Temperatures and Persistent Fog
Thanks to the cool current, Lima’s coastal climate stays mild. Winters see lows around 14 °C, not the typical low twenties of the tropics, while summers average 26 °C, rather than surpassing 30 °C. With relative humidity often above 80%, moist air and fog blanket the city—especially in winter. Lima is, in fact, one of the cloudiest cities globally, logging just 1,230 sunshine hours annually—which is half what cities like Bangkok enjoy.
Why Lima’s Humidity Doesn’t Rain
To understand why humidity doesn’t translate into rain here, recall that warm air holds more moisture than cool air. Rain requires air to rise, cool, and condense—either via storm systems or by being lifted over mountains. However, Lima’s daytime land temperatures, heated by tropical suns, remain warmer than the cool ocean. Any fog or moisture that drifts inland quickly evaporates. Without uplift, Lima’s clouds remain shallow, turning to fog rather than rainfall.
Result: A Never-Raining Tropical Desert
The combination of the rain-blocking Andes and cold Pacific waters creates exceptionally stable atmospheric conditions. The water droplets in Lima’s sky simply don’t collide and grow large enough to become rain. As a result, Lima sits firmly in the BWh (Hot Desert) category of Köppen’s classification: “B” for dry, “W” for desert, and “h” indicating a mean annual temperature above 18 °C. Though some sources have playfully suggested an unofficial “BWn” label for “mild desert,” this is not recognized in peer-reviewed climate studies.
Desert Cities and Water Solutions
Lima isn’t the only city built in a desert, but being in the tropics makes it unique. Despite its arid conditions, the city has managed to grow steadily, thanks to water sourced from Andean springs and rivers, pumped down into the basin. Meanwhile, more remote coastal communities have turned to innovative methods: they install fog nets, which condense moisture from coastal fog into drinkable water—an ingenious workaround to the city’s lack of rainfall.
Conclusion: A Climate Shaped by Nature and Geography
Lima defies expectations—a sprawling tropical metropolis in a near-rainless desert climate. The towering Andes shut out rain-bearing winds, while the cold Humboldt Current chills the coast. The result is a city cloaked in fog, bathed in mild air, and rich in water ingenuity despite its desert classification. Lima’s climate is a masterclass in geography, meteorology, and human adaptation.
What Is a Continental Climate? Everything You Need to Know”
Continental climates are known for their extreme temperature shifts. Summers can be scorching, while winters turn bitterly cold. These regions lie far from the ocean, so they don’t benefit from its moderating influence. Nevertheless, they support hundreds of millions of people and include some of the world’s most productive agricultural zones.
The Geographical Band of Continental Climates
Continental climates stretch across a wide zone in the Northern Hemisphere’s mid-latitudes. This zone runs through Canada’s prairies, the American Midwest, and the vast steppes of Eastern Europe. It continues deep into the Russian interior and reaches Northern China. Interestingly, you won’t find this climate type in the Southern Hemisphere. This absence is due to the lack of large landmasses far enough from the sea.
Temperature Extremes and Clear Seasons
Because oceans can’t influence these areas, temperatures swing wildly throughout the year. Summers are hot and sunny. In contrast, winters bring long freezes and snow. These dramatic changes create one of the clearest four-season cycles on Earth. According to the Köppen classification system, these climates fall under the Dfa and Dfb categories, depending on how warm the summer gets.
Different Types and Rainfall Patterns
There are six main types of continental climates. They vary based on how hot the summer is and when rain falls. While most regions follow a steady pattern, there are some exceptions. For example, a few areas in Central and East Asia experience unusual rainfall rhythms. In some cases, they even resemble Mediterranean or monsoon climates. As a result, the continental climate zone is far more diverse than it might first appear.
Vegetation and Ecosystems
What grows here depends on how much it rains. In drier parts, you’ll see endless grasslands. However, where rainfall increases, forests appear—first mixed woodlands, then thick pine forests farther north. This mix supports vast farms that grow crops like wheat and corn, as well as wild forests that shape the landscape.
Regional Differences Around the World
Continental climates appear in many forms across the globe. In Canada and the U.S. Midwest, for instance, they drive large-scale grain farming and support major cities near the Great Lakes. In Eastern Europe and Western Russia, they fuel agriculture and have shaped cultural life around long winters. Meanwhile, in Northern China, Korea, and Japan, monsoon rains combine with cold winters, creating complex seasonal cycles. Additionally, on the Tibetan Plateau and in eastern Siberia, high altitudes and isolation create rare and extreme versions of this climate.
The Role of Wind and Mountains
Mountains play a key role in shaping this climate. For example, the Rockies block moist air from the Pacific, forcing North America’s rain to come mostly from the south. On the other hand, in Eurasia, winds from the Atlantic bring steady moisture across wide plains. Since there are no major mountain ranges in the way, this moisture travels far inland.
So, continental climates are some of the most dramatic on Earth. Thanks to their sharp seasonal contrasts and diverse ecosystems, they present real challenges. Even so, people not only live in these regions—they thrive. These climates support huge populations and help feed the world. Therefore, they offer a powerful example of how life adapts to even the most extreme conditions.
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Warm summers … but long, dark, cold winters. Here in the far north of the major continents, we find the widest temperature ranges to be found anywhere on earth.
One of the last great wildernesses, the few cities that are here are the coldest on the planet. A place of snow, swamp, lake and trees. These are the lands of the boreal forest. The taiga. Welcome to the subarctic.
Description and Dynamics
In our journey from equator to pole, we have spent the last two chapters looking at the three climates found within the great continents, the cool deserts and the mixed woods and grasslands of the humid continental. It’s now time to take a look at the last of these, the coldest and most northerly of them, the climate of the endless coniferous forests of North America and Eurasia.
The climate itself is referred to as subarctic by most climatologists, but because of the almost exclusive biome of coniferous forest that mark these zones, it often goes by the name of such forests, which are called boreal forest or taiga, the latter word coming from Russian, and which should not be confused with… tiger. Incidentally, tigers live in the taiga – the Siberian Tiger is the largest cat on the planet… But I digress… 🙂
This climate zone houses the world’s largest extent of forests – with almost a third of all trees planetwide found here. They cover in a virtually unbroken sea of dark green, the entire width of the northern continents, from Alaska to Labrador in North America, and from Norway to Siberia and Kamchatka in Eurasia. But opposite to their equatorial cousins – the Tropical Rainforests – these regions have the lowest biodiversity of anywhere on earth, being dominated by often single species trees, such as larch, fir, pine and spruce.
This climate type also occurs in comparatively tiny pockets in more southerly alpine areas, as a result of altitude cooling, specifically in the Rocky Mountains in North America, the Pyrenees, Alps and Carpathians of Europe and the Tibetan plateau in Asia.
Global distribution of Subarctic climate zones with the six Koppen codes
In the Koppen Climate Classification, there are, like the humid continental climates to their immediate south, six divisions of the subarctic climate, separated by patterns of rain and snow and winter temperature. Dominating these six is the one called Dfc, which has year round precipitation – rain in summer, snow in winter, and where at least one full month of the year has an average day/night temperature of 10°C (50°F). This variant accounts for almost 90% of subarctic climate coverage, spanning the entire width of the northern continents.
In the northern Far East, Dfc is supplanted by Dwc, having similar temperatures, but with a monsoon influence pattern of precipitation, with dry winters and wet summers. Yes, the Asian Monsoon makes it this far north, such is the extent of the world’s largest weather system.
10°C might seem like a chilly summer day, but this is a day/night average, and the peak daytime temperature can often exceed 20°C, equivalent to that of the Oceanic climates such as Britain.
Winters are a different story, however. Far from the ocean, and so far north that winter days can be very short, and the nights long, temperatures plummet to -20°C (-4°F) or below as a 24-hour average.
And things only get worse in north-eastern Siberia. Here, we need a colder set of Koppen designations – Dfd and Dwd, because it is here that the winter temperatures fall to the lowest recorded anywhere outside Antarctica. In this classification, winter day/night averages must be below -38°C (-36.4°F), and night lows in winter often fall below -50°C (-58°F). Yet, due to continentality, and long hours of subarctic sunlight, summers here are still surprisingly warm, with peak day temperatures above 23°C (73°F).
Verkhoyansk in NE Siberia has the highest annual temperature range in the world
There is a town in north eastern Siberia that you’ve probably never heard of. But to anyone familiar with climate study, it is well known. Its name is Verkhoyansk, and it is home to the widest recorded temperature range on the planet. Here you can see its rather impressive graph, with a temperature range of summer day to winter night being a staggering 72°C. But this only shows averages. The highest ever recorded temperature here was 38°C (100.4°F) in June 2020, while the lowest was -67.6°C (-89.7°F) – that’s a range of almost 106°C!
The amount of rain falling within these climate zones is usually low in comparison to others, due to continentality. But because of the low average annual temperatures, evaporation of water is low, allowing the growth of hardened coniferous trees which have specialised in their evolution to thrive in these extreme climates. If thrive could be said, because the growing season in these cold climes is limited to just a few short months in summer, and so the trees can take decades to grow to any reasonable size, and usually live for centuries.
Where in the world do we find the Subarctic climates?
So, where in the world are the subarctic climate zones? In short they dominate the northern hemisphere between 50-70 degrees in latitude.
In North America, all but the north coast of Alaska is covered by this climate, along with most of the northern half of the great Canadian plains, from the Yukon in the west to Labrador in the east.
In Europe, this climate dominates Scandinavia, with most of Iceland, all but the oceanic west coast in Norway, the northern two thirds of Sweden and all but the southern fringe of Finland coming under its sway. Iceland is the only notable exception to the rule of the subarctic being covered with pine forest. Once, this island was forested in the same way, but the dependency on the human settlements here on local materials resulted in almost total deforestation of the land centuries ago, leaving a bleak landscape in its place.
Subarctic landscape in Alaska, USA, with the ubiquitous Boreal Forest (Taiga)
Taiga in Finland. Most of this country is within the Subarctic climate type
As we continue east into Russia, the majority of this enormous country is blanketed by the taiga, with the band widening from the northern half of European Russia in the west to encompass all but the frigid northern coasts in the centre and east, in one of the most famous and forbidding regions in the world – Siberia. The subarctic climate extends all the way to the Kamchatka peninsula in the Far East before finishing at the Bering Straits, a stone’s throw from Alaska, where we began.
Landscapes and Vegetation
As mentioned, and obvious from all you have seen in this chapter so far, this climate is virtually synonymous with the boreal forest, or taiga. Patterns in this seemingly homogenous forest do exist, however. Different species of trees tend to dominate different regions – spruces in North America, for example, while eastern Siberia and its extreme winter temperatures is dominated by the hardiest conifers of all… the Siberian Larch.
In the south the taiga gradually gives way to mixed woodland and deciduous forest, such as in Eastern Canada, or to grasslands where there is more aridity, such as in Central Russia or east of the Rockies. In the north, even the trees eventually give way to the barren grasses of the Tundra, which we’ll take up in the next chapter.
Due to the low evaporation rates in this land of weak sun, the rain and snow that does fall in the flat basins that dominate the upper latitudes tends to persist, forming large swamps, bogs or lakes. If you’ve ever looked at a map of Finland or Northern Canada, then you’ll have noticed this. Such areas of standing water are havens for mosquito breeding, and much of Siberia is particularly plagued by such creatures in summer, just in case you were thinking this respite from the frozen conditions might make for a pleasant camping trip.
Because of the long winters, the ground is permanently frozen below a certain depth. This is known as permafrost. The depth at which it is frozen depends on latitude – with more southerly regions having soil with a thinner layer of ice at a deeper level compared to more northerly areas where the ice is thicker and closer to the surface. On average, the ground stays frozen just a few feet below the surface. We’ll talk more about the permafrost in the next chapter.
Farming in such conditions is extremely difficult and there is almost no farming on any scale worth mentioning in these bleak regions.
Notable places with Subarctic Climates
Human Settlement
These factors in combination make the subarctic a forbidding place in regard to human settlement, and so these areas are consequently very sparsely populated, the exceptions being where the location has specific strategic advantage or where rich natural resources are found.
There are only four cities of any size worthy of mention here. Anchorage Alaska has grown over the last hundred years as a rail and aviation hub, and with its coastal location, the climate is relatively moderate under the maritime influence. Murmansk, a significant strategic naval base on the arctic coast of Russia by Scandinavia, and the largest city above the arctic circle, is similarly moderated by an ice-free sea.
This is not true for the other two major cities in the subarctic. Norilsk, a metallurgical mining centre in Northern Siberia is the most northerly city above 100,000 population and is regarded as the coldest city in the world by its average temperature year round of nearly minus 10 degrees celsius. Lastly, Yakutsk, a diamond mining centre in Eastern Siberia has the coldest winters of any major city in the world with a day/night average in January of almost -39°C (-38°F). Fun times.
Coursework Questions
What are the main differences between the subarctic climate and the continental climates to the south?
Explain the logic behind the six Continental Koppen climate codes, detailing the three rainfall distribution letters and two temperature range letters. Which is the most important of the six?
Why do places like Verkhoyansk in NE Siberia have such extreme annual temperature ranges?
What is the dominant form of vegetation in the subarctic?
List out some countries and areas that experience subarctic climates.
The treeless Arctic. A desolate region, where few things grow. Yet, rich in fauna, both on the land, and at sea, and is the home of an iconic animal in this world of climatic uncertainty.
A famous people survive here toughing it out in the most hostile populated climate on earth. A barren land of ice, lake, swamp and grass. This is the northern tip of our planet… this is the tundra.
Description and Dynamics In the last chapter we looked at the subarctic lands dominated by the boreal forest, the taiga. Now, as we travel even further north in our journey from equator to pole, we arrive in the true Arctic itself, and this region is dominated by the treeless expanse known as the tundra.
Our word for this biome, like the Taiga of the Sub-Arctic, is also borrowed from Russian, with roots in the Sami word for “treeless uplands”. But whereas the Taiga is dominated by enormous forest, the tundra, by contrast, and by definition, is devoid of trees, and is a bleak land consisting only of dwarf shrubs, hardy grasses, mosses and lichen.
The reason that trees cannot grow here is simple – it’s too cold. And by this, specifically, we mean that summer temperatures must be above 10 degrees C for at least a month in summer in order for trees to complete their necessary seasonal cycles. But for anything to grow at all, temperatures must be above freezing. And these two temperature points give us the climatic definition of the tundra – summer temperatures must be between 0 and 10 degrees.
Global distribution of the Tundra climate zone
Interestingly, winter temperatures are not as extreme as some of those found in the sub-arctic regions of north-eastern Siberia. This is because the tundra areas are never that far from the coasts of the arctic ocean, and so are moderated somewhat, even though this ocean is ice covered for half the year or more.
Average temperatures in the tundra, like in the sub-arctic, are cold enough to produce a layer of permanently frozen soil throughout the year, known as permafrost. This is another factor limiting the growth of more substantial plants which would otherwise demand deeper root structures.
The tundra is very low in precipitation, comparable to desert and semi-arid regions closer to the equator. But because of the low evaporation rates from such low temperatures, and the barrier of the permafrost preventing proper drainage, water stays around, allowing many dwarf species of plants to grow.
Where in the world do we find the Tundra climate? So, where in the world can we find the tundra? The classic tundra, with cool summers and very cold winters that produces the permafrost, is found only in the arctic, and includes the northern coast of Alaska, almost all the northern coast and islands of Canada, the coasts of Greenland, Svalbard – a large island north of Norway, and most of the northern coasts of Russia.
Tundra in summer, near Nome, Alaska. Image courtesy of IBWOVids
Nuuk, the capital of Greenland, the largest city in the Tundra. Image courtest of Reimund Langgaard
Cape Horn, at the tip of South America, has a type of Tundra where summer temperatures barely reach 10°C, but unlike the Arctic Tundra, has no winter frosts
In the uplands of Iceland and Norway, and at high altitudes in the Alps and Himalayas, summer temperatures are so cold, that tree growth is not possible, and so these areas have a form of tundra as Alpine meadows, although no permafrost exists here.
The southern tip of South America, and the coasts of the Antarctic peninsula also have tundra-like conditions, but without permafrost. These areas, however, are really slightly colder versions of the sub-polar Oceanic climate (the Koppen Cfc) that we talked about in Chapter 7, because winter temperatures here rarely fall below freezing, despite summer temperatures staying below 10°C, due to the heavy moderating influence of the Southern Ocean.
Landscapes and Vegetation So what landscapes and vegetation do we find in the Arctic? The absence of trees leads to stark vistas of empty plains and bare mountains, covered only by hardy low-lying grasses, moss, lichen, and low-lying shrubs, the latter occurring in the warmer section of the tundra bordering on the taiga.
The permafrost – permanently frozen ground from a few inches to a few feet below the surface in summer and going down to depths of up to hundreds of metres, not only inhibits plant root growth, but also prevents drainage, resulting in a patchwork of lakes, bogs and swamps in flat areas.
Notable settlements with the Tundra climate
Due to the short summer, the growing season lasts only for about two months, so the hardy plants that live here must flower as soon as possible after the long freezing winter.
Farming in such a harsh climate is non-existent – the few people that live in these regions, such as the Inuit of North America, rely upon the hunting of animals – seals, caribou, whales, fish, and even polar bears, among others, to feed themselves.
There are no major cities to be found in these regions – the largest settlement being Nuuk (formerly Godthaab), the capital of Greenland, with around 18,000 population.
Coursework Questions
Why can’t trees grow in the Tundra?
How does the Tundra climate differ from the Subarctic? Why are the tundra winters sometimes not as severe compared to the subarctic?
What is the permafrost and how does it influence the landscape?
What are the natural biomes and landscapes in these climate zones?
List out some regions that experience the Tundra climate.
