D. Earth and Space Science: Climate Change · Climate ChangeClassifying Your Local Climate: Climographs, Köppen and Canada's Ecozones
D2.8 D2.1 A1.6 A1.12About 70 minutes
Learning goals- I can name the main factors that control a region's climate.
- I can build and interpret a climograph from climate normals.
- I can classify a climate using the Köppen system.
- I can use tools such as the Ecozones and Ecoregions of Canada, bioclimate profiles and plant hardiness zones to describe my local climate.
- I can compare my local climate with other regions in Ontario, Canada and the world.
Words to know
climate normals
Averages of weather data (such as monthly temperature and precipitation) over a standard 30-year period.
climograph
A graph showing a place's monthly average temperature (as a line) and monthly precipitation (as bars).
annual temperature range
The difference between the warmest and coldest monthly average temperatures.
continental climate
A climate far from the moderating effect of oceans, with a large annual temperature range.
maritime climate
A climate moderated by a nearby ocean, with a small annual temperature range.
Köppen classification
A widely used system that classifies climates by temperature and precipitation, using letter codes such as Dfb.
ecozone
A very large area of Canada with similar climate, landforms, soils, plants and animals; Canada has 15 land-based ecozones.
ecoregion
A smaller part of an ecozone, defined by its particular climate, landforms and vegetation.
growing degree days
A measure of how much warmth is available for plant growth, adding up how many degrees each day's mean temperature is above a base (often 5 °C).
Let's start with a question you can answer
How would you describe the climate where you live to someone in Brazil or Australia? "Cold" isn't enough. Is it cold all year or just in winter? How much precipitation falls, and when? How long is the growing season?
Scientists use standard tools so that climates can be described and compared consistently, anywhere in the world. In this lesson you'll learn several of them and use them on your own community.
What controls a region's climate?
You've already met most of the controls in Lessons 1 to 5. Geographers often summarize them with the memory aid LOWERN:
- Latitude: the Sun's angle and day length (Lesson 1).
- Ocean currents: warm or cold water offshore (Lesson 5).
- Winds and air masses: prevailing winds and where air comes from (Lesson 3).
- Elevation: temperature drops with height (Lesson 2).
- Relief: mountains cause orographic precipitation and rain shadows (Lesson 4).
- Nearness to water: large lakes and oceans moderate temperature (Lessons 2 and 4).
Any place's climate is the result of all six working together.
Climate normals and climographs
Climate is described with climate normals: 30-year averages of measurements such as monthly temperature and precipitation. Environment and Climate Change Canada publishes Canadian Climate Normals for hundreds of weather stations across the country.
A climograph puts the two most important climate variables on one graph:
- Bars for monthly precipitation (right axis, mm).
- A line for monthly mean temperature (left axis, °C).
From a climograph you can read the annual mean temperature (average of the 12 months), the annual temperature range (warmest month − coldest month), the total annual precipitation (sum of the 12 bars), and the seasonal pattern (Is there a dry season? When is the wettest month?).
| Month | J | F | M | A | M | J | J | A | S | O | N | D |
|---|
| Temp (°C) | −6 | −5 | 0 | 7 | 13 | 19 | 22 | 21 | 17 | 10 | 4 | −2 |
| Precip (mm) | 65 | 55 | 60 | 75 | 80 | 85 | 80 | 80 | 85 | 70 | 80 | 70 |
Worked exampleExample 1: Reading the Maple Lake climograph
Use the Maple Lake data to find the annual mean temperature, annual temperature range and total annual precipitation. Describe the seasonal pattern.
- Annual mean temperature: add the 12 monthly means: −6 − 5 + 0 + 7 + 13 + 19 + 22 + 21 + 17 + 10 + 4 − 2 = 100. Divide by 12: 100 ÷ 12 ≈ 8.3 °C.
- Annual range: warmest (July, 22 °C) − coldest (January, −6 °C) = 22 − (−6) = 28 °C.
- Total precipitation: 65 + 55 + 60 + 75 + 80 + 85 + 80 + 80 + 85 + 70 + 80 + 70 = 885 mm.
- Pattern: warm summers, cold winters (below 0 °C for three months), and precipitation spread fairly evenly through the year (no dry season), a little higher in late spring and summer. In winter much of it falls as snow.
Mean ≈ 8.3 °C; range = 28 °C; total = 885 mm; four distinct seasons with no dry season.
The Köppen climate classification
The Köppen system, first developed by the climatologist Wladimir Köppen over a century ago and refined since, is still the most widely used world climate classification. It uses letters:
- A: tropical (every month 18 °C or warmer)
- B: dry (deserts and steppes, where evaporation exceeds precipitation)
- C: temperate (coldest month between −3 °C and 18 °C)
- D: continental (coldest month below −3 °C, warmest month at least 10 °C)
- E: polar (warmest month below 10 °C); ET is tundra (warmest month between 0 °C and 10 °C)
A second and third letter add detail. For C and D climates: f means no dry season; a means a hot summer (warmest month 22 °C or more); b means a warm summer (warmest month below 22 °C, with at least four months at 10 °C or more); c means a short, cool summer (only one to three months at 10 °C or more).
Some versions of Köppen use 0 °C instead of −3 °C as the C/D boundary; always say which version you're using.
Worked exampleExample 2: Classify four practice stations
Use the simplified key (with −3 °C as the C/D boundary) to classify these stations. None is dry enough to be B.
- Maple Lake: coldest −6 °C, warmest 22 °C, precipitation spread through the year.
- Cedar Cove: monthly temps 4, 5, 7, 9, 12, 15, 17, 18, 15, 10, 6, 4 °C; driest month 40 mm, no dry season.
- Spruce Bay: monthly temps −24, −22, −15, −5, 3, 10, 14, 13, 7, 0, −10, −20 °C; no dry season.
- Ice Point: warmest month 7 °C.
- Maple Lake: warmest ≥ 10 °C (not E). Coldest −6 °C < −3 °C → D. No dry season → f. Warmest month 22 °C ≥ 22 → a. Climate: Dfa (hot-summer continental).
- Cedar Cove: warmest 18 °C ≥ 10 (not E). Coldest 4 °C is not below −3 °C (not D) and not 18 °C or more (not A) → C. No dry season → f. Warmest 18 °C < 22; months at 10 °C or more: May (12), June (15), July (17), August (18), September (15), October (10) = 6 months → b. Climate: Cfb (marine west coast), like coastal B.C.
- Spruce Bay: warmest 14 °C (not E). Coldest −24 °C → D, f. Warmest < 22; months ≥ 10 °C: June (10), July (14), August (13) = only 3 → c. Climate: Dfc (subarctic), like much of northern Ontario.
- Ice Point: warmest 7 °C < 10 °C → E. Between 0 and 10 °C → ET (tundra), like parts of the Arctic.
Maple Lake Dfa, Cedar Cove Cfb, Spruce Bay Dfc, Ice Point ET.
Monthly temperatures for three practice stations. The coastal station's line is flat (small annual range: 14 °C); the inland stations swing much more (28 °C and 38 °C). Distance from water matters, not just latitude.Canadian tools: ecozones, ecoregions, bioclimate profiles and hardiness zones
Köppen uses only temperature and precipitation. Canadian scientists have also developed tools that combine climate with landforms, soils and living things.
Ecozones and ecoregions of Canada. The national ecological framework divides Canada into 15 terrestrial (land) ecozones, such as the Arctic Cordillera, Taiga Shield, Boreal Shield, Prairies, Pacific Maritime and Mixedwood Plains. Each ecozone is divided into smaller ecoprovinces, ecoregions and ecodistricts. Climate is one of the main factors used to draw the boundaries.
Ontario has parts of three national ecozones:
- Hudson Plains in the far north (flat, wet, with extensive peatlands and permafrost near Hudson Bay),
- Boreal Shield, covering most of the province (rocky Canadian Shield, lakes and boreal forest),
- Mixedwood Plains in the south (the warmest part of Ontario, with deciduous and mixed forests and most of the farmland and population).
Ontario's own provincial framework uses similar zones (Hudson Bay Lowlands, Ontario Shield, Mixedwood Plains) divided into numbered ecoregions. For example, ecoregion 7E, along Lake Erie and western Lake Ontario, is the warmest in the province and is home to Carolinian forest species such as tulip tree and sassafras.
Bioclimate profiles. The Canadian Forest Service has produced bioclimate profiles: sets of graphs that summarize the climate variables that matter most to living things at a location, such as growing season length, growing degree days and moisture. Many include both past climate and projections for future decades, so foresters and farmers can see how their local climate may change.
Plant hardiness zones. Natural Resources Canada maps plant hardiness zones (from 0, harshest, to 9, mildest) based on climate variables such as winter minimum temperatures, the frost-free period and snow cover. Gardeners use them to choose plants that will survive the winter.
| Tool | What it uses | What it tells you |
|---|
| Climograph | Monthly temperature and precipitation normals | Seasonal pattern, range, totals |
| Köppen | Temperature and precipitation thresholds | A letter code you can compare worldwide |
| Ecozones and ecoregions | Climate plus landforms, soils, vegetation, wildlife | Where you are in Canada's ecological framework |
| Bioclimate profile | Climate variables important to plants and animals, past and projected | Growing season, warmth, moisture, future change |
| Plant hardiness zone | Winter cold, frost-free period, snow and other variables | Which plants can survive |
Worked exampleExample 3: Growing degree days
Growing degree days (GDD) above 5 °C are found by adding up (daily mean temperature − 5) for every day warmer than 5 °C (days at or below 5 °C count as 0). Find the GDD for this week in May: 8, 12, 15, 4, 10, 14, 17 °C.
- Subtract 5 from each: 3, 7, 10, (4 − 5 is negative, so 0), 5, 9, 12.
- Add: 3 + 7 + 10 + 0 + 5 + 9 + 12 = 46.
- Over a whole season, southern Ontario typically accumulates far more growing degree days than northern Ontario, which is one reason crops like corn and soybeans are grown mainly in the south.
46 growing degree days for the week.
Just for funWladimir Köppen was trained as a botanist, and he drew his climate boundaries partly by looking at where different kinds of plants grow. So, in a way, the world's most famous climate map was co-written by the trees.
Hands-on activityClassify your own climate (A1.6, A1.12)
You need: internet access with a grown-up's OK, graph paper or a spreadsheet, a calculator.
- Find the Canadian Climate Normals for the weather station nearest your home (Environment and Climate Change Canada website). Record the 12 monthly mean temperatures and precipitation totals in a table with units.
- Make a climograph: precipitation bars on the right axis, temperature line on the left axis, title, labelled axes.
- Calculate the annual mean temperature, annual range and total precipitation. Round sensibly (one decimal place for temperatures).
- Classify your climate with the Köppen key in this lesson. Show which rule you used for each letter.
- Find your ecozone and, if you can, your ecoregion, and your plant hardiness zone (Natural Resources Canada).
- Compare: get the same data for one other place in Ontario (for example, Moosonee if you live in the south, or Windsor if you live in the north), one other place in Canada (for example, Victoria, Winnipeg or Iqaluit) and one place elsewhere in the world. Put all four in a comparison table and write a paragraph explaining the differences using LOWERN.
What to look for: a correctly drawn climograph with both axes labelled, correct calculations, a Köppen code with reasons, and explanations that name specific controls ("Moosonee's colder winters are mainly due to its higher latitude and the cold waters of James Bay, which are frozen much of the winter").
Your turn
1What does LOWERN stand for?
Latitude, Ocean currents, Winds and air masses, Elevation, Relief, Nearness to water.
2Why are climate normals averaged over 30 years instead of one year?
One year can be unusually warm, cold, wet or dry. Averaging over 30 years smooths out year-to-year variability and describes the typical climate.
3On a climograph, what do the bars and the line usually show?
Bars: monthly precipitation (mm). Line: monthly mean temperature (°C).
4A station's monthly means range from −14 °C (January) to 19 °C (July). What is its annual range?
5Which Köppen letter describes a climate where the warmest month is below 10 °C?
6Name the three national ecozones found in Ontario, from north to south.
Hudson Plains, Boreal Shield, Mixedwood Plains.
7Why do coastal places usually have a smaller annual temperature range than inland places?
Nearby water heats and cools slowly (high specific heat capacity), keeping summers cooler and winters milder.
More practice: warm-up
1How many years are used for climate normals?
2Which Köppen letter is used for tropical climates?
3Which Canadian government department publishes Canadian Climate Normals?
Environment and Climate Change Canada.
4What does the "f" mean in Dfb?
No dry season (precipitation in all seasons).
5How many land-based (terrestrial) ecozones does Canada have?
More practice: on your own
1Classify a station with coldest month −12 °C, warmest month 20 °C, five months at 10 °C or more, and no dry season.
Coldest below −3 °C → D; no dry season → f; warmest < 22 °C with at least 4 months ≥ 10 °C → b. Dfb.
2Classify a station with monthly means all between 25 °C and 28 °C and heavy rain in every month.
Coldest month ≥ 18 °C → A (tropical); with rain all year it is a tropical rainforest climate (Af).
3Find the annual mean temperature for Cedar Cove (4, 5, 7, 9, 12, 15, 17, 18, 15, 10, 6, 4 °C).
Sum = 122. Mean = 122 ÷ 12 ≈ 10.2 °C.
4Find the growing degree days (base 5 °C) for: 6, 9, 3, 11, 14 °C.
5Two Ontario towns are at the same latitude, but one is on the shore of Lake Huron and one is 150 km inland. Predict two differences in their climographs and explain.
The lakeshore town would have a smaller annual range (cooler summers, milder winters) because the lake moderates temperature. It might also have more winter precipitation (lake-effect snow) if it's on the downwind (east) shore. The inland town would have hotter summers and colder winters.
Challenge
1Using the −3 °C boundary, Cedar Cove is Cfb. Suppose global warming raised every Spruce Bay monthly mean by 3 °C. Would its Köppen class change? Show your reasoning.
New values: −21, −19, −12, −2, 6, 13, 17, 16, 10, 3, −7, −17. Coldest −21 → still D, f. Warmest 17 < 22. Months ≥ 10 °C: June 13, July 17, August 16, September 10 = 4 months → now b instead of c. Spruce Bay would change from Dfc to Dfb. This is how climate zones shift north as the climate warms.
2Explain why a climate classification based only on temperature and precipitation (like Köppen) may not fully describe a region, and how ecozones add information.
Köppen ignores factors such as soil, landforms, permafrost, the length of daylight, snow cover, wind and the plants and animals present. Two places with the same Köppen code can look very different (for example, rocky Canadian Shield versus flat farmland). Ecozones combine climate with landforms, soils, vegetation and wildlife, so they describe whole ecosystems, which is more useful for conservation and land planning.
3Bioclimate profiles often show projected future climate for a location. A profile shows that a town's growing degree days may increase by 30% by the 2050s. Give one possible benefit and two possible challenges for the town.
Benefit: farmers may be able to grow longer-season or new crops (for example, more corn, soybeans or tender fruit). Challenges: more pests and diseases that survive milder winters; heat stress and drought during hotter summers; native trees and wildlife adapted to the old climate may struggle; more water needed for irrigation.
Quiz
1. On a climograph, the bars usually show...
2. A station's coldest month is −9 °C and its warmest is 21 °C, with five months at 10 °C or more and no dry season. What is its Köppen class?
3. Which statement best describes a continental climate?
4. Which national ecozone covers most of Ontario?
5. Why are climate normals based on 30 years of data?
6. What is the annual mean temperature of a place with monthly means that add up to 60 °C?
Big idea: Climates can be described and compared with standard tools: climographs, the Köppen classification, Canada's ecozones and ecoregions, bioclimate profiles and plant hardiness zones. This covers D2.8 (classify the local climate and compare it with other regions) and builds data skills (A1.6, A1.12).
How to help: Help your teen find the climate normals for your area; the Environment and Climate Change Canada website lets you search by station name. A spreadsheet makes the climograph easier. Ask: "How would our climate graph look different if we lived on the B.C. coast? In Nunavut?"
Common difficulties:
- Subtracting negative numbers when finding the annual range (22 − (−6) = 28).
- Forgetting to check the warmest-month rule for E before checking D.
- Thinking all of Ontario has the same climate; the north and south differ a lot.
The practice stations (Maple Lake, Cedar Cove, Spruce Bay, Ice Point) are made up so the numbers are easy to work with; real data are in the activity.