What a Csb climate is like
Csb Warm-summer Mediterranean. Like the hot-summer Mediterranean climate, but summers are a little cooler, often because of cool ocean currents or altitude.
The rules behind the code, in plain English:
- Temperate (coldest month between 0 °C and 18 °C).
- Dry summer: the driest summer month gets under 40 mm and under a third of the wettest winter month.
- Warm summer: the warmest month is under 22 °C, and at least four months are above 10 °C.
Dataset wording: "Temperate, dry summer, warm summer". In the maps of Beck et al. (2023) the class is written: C: Not B and Thot > 10 and 0 < Tcold < 18; s: Psdry < 40 and Psdry < Pwwet/3; b: Not a and Tmon10 >= 4.
Warm-summer Mediterranean climate has dry summers that are warm rather than scorching, and mild, wetter winters. Cool sea air or altitude keeps the heat in check, so the summers are pleasant and sunny. Vines, olives, orchards and evergreen woodland grow well, and gardens need watering in summer. Light layers cover most of the year, with a waterproof for the wetter months.
How much of the world is Csb?
- 0.8%of the world's land outside Antarctica, 1991 to 2020
- 1,028,122 km²area, 1991 to 2020
- 643cities of 15,000 or more people (GeoNames) have this climate now
In 1901 to 1930 it covered 1% of that land, so its area then was 32.02% larger than in 1991 to 2020.
How the Csb area is projected to change by 2071 to 2099
These figures compare the area of Csb in each future map with 1991 to 2020. They come from the Beck et al. (2023) model projections under three emissions scenarios. They show what the scenarios imply, not what will happen.
| Map | Share of land | Change in area vs 1991 to 2020 |
|---|---|---|
| 1901 to 1930 (past) | 1% | +32.02% |
| 1991 to 2020 (now) | 0.8% | - |
| 2071 to 2099, SSP1-2.6 (low emissions) | 0.6% | -25.27% |
| 2071 to 2099, SSP2-4.5 (middle of the road) | 0.5% | -37.05% |
| 2071 to 2099, SSP5-8.5 (high emissions) | 0.3% | -56.59% |
Shares are of land outside Antarctica. A negative change means the zone shrinks.
What happens to today's Csb land
Of the land that is Csb in 1991 to 2020, this is how much stays Csb and where the rest ends up in 2071 to 2099, by scenario:
| Scenario (2071 to 2099) | Stays Csb | Where the rest goes (biggest first) |
|---|---|---|
| SSP1-2.6, low emissions | 64% | Csa (20%), Aw (5.7%), Cfb (4.3%), Am (1.6%), BSk (1.6%) |
| SSP2-4.5, middle of the road | 49% | Csa (31%), Aw (8.9%), BSk (3.1%), Cfb (3%), Am (2.8%) |
| SSP5-8.5, high emissions | 26% | Csa (45%), Aw (11%), BSk (5.8%), Am (4.8%), BSh (3%) |
Looking back, 86% of today's Csb land was also Csb in 1901 to 1930. The rest was Dsb (5.9%), Cfb (3.5%), Cwb (2.5%).
Where Csb is found
The countries with the most Csb land in 1991 to 2020:
| Country | Area | Share of all Csb | Share of the country |
|---|---|---|---|
| United States | 217,655 km² | 21% | 2.3% |
| Ethiopia | 118,429 km² | 12% | 10% |
| Australia | 113,041 km² | 11% | 1.5% |
| Chile | 107,680 km² | 10% | 15% |
| Spain | 104,796 km² | 10% | 21% |
| Argentina | 83,792 km² | 8.2% | 3% |
| Portugal | 34,626 km² | 3.4% | 38% |
| Kenya | 30,069 km² | 2.9% | 5.1% |
Places with a Csb climate today
The biggest cities in the 1991 to 2020 map that sit in Csb (at most two per country):
- Cape Town, South Africa
- Quito, Ecuador
- Adelaide, Australia
- San Jose, United States
- San Francisco, United States
- Nakuru, Kenya
- Lisbon, Portugal
- Eldoret, Kenya
- Viña del Mar, Chile
- Vigo, Spain
- Victoria, Canada
- Valparaíso, Chile
Other temperate climates (group C)
Frequently asked questions
What does Csb mean in the Köppen climate classification?
Temperate (coldest month between 0 °C and 18 °C). Dry summer: the driest summer month gets under 40 mm and under a third of the wettest winter month. Warm summer: the warmest month is under 22 °C, and at least four months are above 10 °C. The code is a short way of writing that: the first letter is the major group (C, temperate) and the letters after it say more about rain and temperature.
What is a warm-summer mediterranean climate like?
Dry, warm summers and mild, wetter winters. Like the hot-summer Mediterranean climate, but summers are a little cooler, often because of cool ocean currents or altitude.
How much of the world has a Csb climate?
0.8% of the world's land outside Antarctica was Csb in 1991 to 2020, about 1,028,122 km² (Beck et al. 2023, 1 km maps).
Will the Csb climate zone grow or shrink?
Under the middle-of-the-road scenario (SSP2-4.5), the area of Csb in 2071 to 2099 is 37.05% smaller than in 1991 to 2020. This is a model projection, not a forecast, and it differs under other scenarios (see the table on this page).
Data: Beck et al. (2023), CC BY 4.0. See data sources and licences. Köppen-Geiger classes describe long-term averages, not weather.