What a Dfa climate is like
Dfa Hot-summer humid continental. A big seasonal swing. Summers can be hot and humid, winters are cold with snow, and there is no dry season.
The rules behind the code, in plain English:
- Cold (coldest month at or below 0 °C).
- No dry season (neither a dry summer nor a dry winter as defined above).
- Hot summer: the warmest month averages 22 °C or more.
Dataset wording: "Cold, no dry season, hot summer". In the maps of Beck et al. (2023) the class is written: D: Not B and Thot > 10 and Tcold <= 0; f: Not Ds or Dw; a: Thot >= 22.
Hot-summer humid continental climate has hot summers and cold winters, with rain all year. Summers are warm and humid, winters bring snow and hard frost, and spring and autumn can be sharp. Maize, soya beans and wheat grow on rich farmland, and forests are broadleaf. Homes need both heating and cooling, and wardrobes cover the whole range from heavy coats to light summer clothes.
How much of the world is Dfa?
- 1.8%of the world's land outside Antarctica, 1991 to 2020
- 2,358,313 km²area, 1991 to 2020
- 1,665cities of 15,000 or more people (GeoNames) have this climate now
In 1901 to 1930 it covered 1.4% of that land, so its area then was 17.73% smaller than in 1991 to 2020.
How the Dfa area is projected to change by 2071 to 2099
These figures compare the area of Dfa 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) | 1.4% | -17.73% |
| 1991 to 2020 (now) | 1.8% | - |
| 2071 to 2099, SSP1-2.6 (low emissions) | 2.7% | +54.21% |
| 2071 to 2099, SSP2-4.5 (middle of the road) | 3.6% | +106.38% |
| 2071 to 2099, SSP5-8.5 (high emissions) | 8.1% | +363.41% |
Shares are of land outside Antarctica. A negative change means the zone shrinks.
What happens to today's Dfa land
Of the land that is Dfa in 1991 to 2020, this is how much stays Dfa and where the rest ends up in 2071 to 2099, by scenario:
| Scenario (2071 to 2099) | Stays Dfa | Where the rest goes (biggest first) |
|---|---|---|
| SSP1-2.6, low emissions | 74% | Cfa (21%), BSk (5%) |
| SSP2-4.5, middle of the road | 52% | Cfa (37%), BSk (11%), Dsa (0.5%) |
| SSP5-8.5, high emissions | 23% | Cfa (53%), BSk (23%), Dsa (0.7%) |
Looking back, 65% of today's Dfa land was also Dfa in 1901 to 1930. The rest was Dfb (30%), Dwa (3.2%), BSk (1.5%).
Where Dfa is found
The countries with the most Dfa land in 1991 to 2020:
| Country | Area | Share of all Dfa | Share of the country |
|---|---|---|---|
| United States | 1,275,740 km² | 54% | 14% |
| Russia | 449,597 km² | 19% | 2.7% |
| Ukraine | 213,363 km² | 9.1% | 37% |
| Kazakhstan | 188,182 km² | 8% | 7% |
| Romania | 69,778 km² | 3% | 30% |
| Japan | 50,546 km² | 2.1% | 14% |
| Hungary | 29,455 km² | 1.3% | 32% |
| Canada | 27,500 km² | 1.2% | 0.3% |
Places with a Dfa climate today
The biggest cities in the 1991 to 2020 map that sit in Dfa (at most two per country):
Other cold (continental) climates (group D)
- Dsa Hot-summer continental with dry summer
- Dsb Warm-summer continental with dry summer
- Dsc Subarctic with dry summer
- Dsd Subarctic with dry summer and very cold winter
- Dwa Hot-summer continental with dry winter
- Dwb Warm-summer continental with dry winter
- Dwc Subarctic with dry winter
- Dwd Subarctic with dry winter and very cold winter
- Dfb Warm-summer humid continental
- Dfc Subarctic (boreal)
- Dfd Subarctic with very cold winter
- All 30 zones
Frequently asked questions
What does Dfa mean in the Köppen climate classification?
Cold (coldest month at or below 0 °C). No dry season (neither a dry summer nor a dry winter as defined above). Hot summer: the warmest month averages 22 °C or more. The code is a short way of writing that: the first letter is the major group (D, cold (continental)) and the letters after it say more about rain and temperature.
What is a hot-summer humid continental climate like?
Hot summers and cold winters, with rain all year. A big seasonal swing. Summers can be hot and humid, winters are cold with snow, and there is no dry season.
How much of the world has a Dfa climate?
1.8% of the world's land outside Antarctica was Dfa in 1991 to 2020, about 2,358,313 km² (Beck et al. 2023, 1 km maps).
Will the Dfa climate zone grow or shrink?
Under the middle-of-the-road scenario (SSP2-4.5), the area of Dfa in 2071 to 2099 is 106.38% larger 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.