A climate graph shows the pattern of rainfall and temperature through a year. To interpret it, describe the pattern, quote the extremes with figures, and calculate a total or a range when asked.
This lesson is part of physical geography. It also practises the graph skills covered in map and graph skills.
What is the method?
- Read the axes and units.
- State the overall pattern in one sentence.
- Quote the highest and lowest months with values.
- Calculate the range or total, showing the subtraction or sum.
- Add one comparison, such as wetter months against drier months.
Worked example: an original station
An original Station K gives monthly rainfall (mm) from January to December: 280, 190, 210, 240, 180, 120, 110, 130, 170, 250, 310, 330. Its monthly mean temperature stays between 26.2 °C in January and 28.4 °C in May.
Total rainfall: 280 + 190 + 210 + 240 + 180 + 120 + 110 + 130 + 170 + 250 + 310 + 330 = 2 520 mm.
Rainfall range: wettest December 330 mm, driest July 110 mm, so the range is 330 − 110 = 220 mm.
Temperature range: 28.4 − 26.2 = 2.2 °C.
Pattern sentence: “Station K is warm and wet all year. Temperature varies by only 2.2 °C, while rainfall is highest in December at 330 mm and lowest in July at 110 mm. No month has less than 110 mm.”
The mistake: a description without figures
A common slip is to write “it rains a lot and it is hot”. The sentence is true, but a marker cannot credit it, because nothing links it to the graph.
| Vague | Quoted |
|---|---|
| “Rainfall is high” | “Rainfall peaks at 330 mm in December” |
| “Temperature is steady” | “Temperature changes by only 2.2 °C across the year” |
| “Some months are drier” | “July is driest at 110 mm, 220 mm below December” |
A second slip is to read temperature from the rainfall axis. Check which axis belongs to which data before you read a value.
Check yourself
An original Station T has monthly rainfall (mm) from January: 40, 30, 20, 60, 120, 180, 210, 200, 150, 90, 50, 40. Find the total rainfall, the wettest and driest months and the range, and describe the pattern in one sentence.
Answer
Total: 40 + 30 + 20 + 60 + 120 + 180 + 210 + 200 + 150 + 90 + 50 + 40 = 1 190 mm.
Wettest: July, 210 mm. Driest: March, 20 mm. Range: 210 − 20 = 190 mm.
Pattern: “Rainfall has a clear wet season from May to September, with 120 mm or more each month and a peak of 210 mm in July, and a drier season with 60 mm or less from November to April.”
What to study next
Move on to connecting processes with observed features, where graphs and field features feed the same explanation. You can also test yourself with the map and graph reading practice.
If you want a teacher to go through your graph answers with you, see online one-to-one Geography tuition.