How to Read and Interpret Contour Maps

This page shows how to use the contour maps to determine values of temperature, cloud clover or rainfall at any location.

Colors on the map are related to temperature (or rainfall, or cloud cover) by the colorbar at the bottom or side of each image. Look at the following colorbar:

The label at the bottom shows that the colorbar (and the image it refers to) represents the maximum temperature (in degrees Celsius) for November 15. Notice that the colorbar is labeled at the top with numbers like -12, -9, -6, etc. These numbers show the temperature range that is represented by each color. For instance, the bright green color (marked with a plus sign, +) means that the temperature is between 18 and 21 degrees Celsius.

Using the colorbar shown above, test yourself to see if you can determine the temperatures at the points labeled A, B, C, D, and E? The answers (and explanation) are at the bottom of the page.

We will do the first one (point A) here: Note that point A is located in the area that is bright green. Looking at the colorbar, we see that this is the same color that is marked by the + sign. Therefore, the maximum temperature at point A on November 15 was between 18 and 21 degrees Celsius.

Answers to the Questions:

1. The temperature at point B is between 3 and 6 degrees Celsius.
2. The temperature at point C is just about 0 degrees Celsius (note that point C is located on the boundary between 2 colors. The lower color represents temperatures between -3 and 0 degrees, while the upper color represents temperatures between 0 and 3 degrees).
3. Points D and E are both within the same color, which represents a range of 0 to 3 degrees Celsius. However, notice that point D is close to the next lower color, while point E is closer to the next higher color. This means than point E is warmer that point D. Point E is probably close to 2 degrees Celsius while point D is close to 1 degree Celsius.

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