The temperature is indicated by a colour scale

A box-like structure called a 'Stevenson screen' is often used to protect meteorological instruments against exposure to direct sunlight, precipitation, and condensation, while at the same time providing adequate ventilation. Instrument shelters are painted white, have louvered sides (slats) and usually a double roof. A Stevenson screen may be mounted on a stand above the ground with the door side facing north.  
 
If you don't have access to such a shelter, you can measure the temperature sheltered from wind and sun. Be sure to hold the thermometer (especially its base) away from your body to prevent it being influenced by your body temperature.

Weather symbol on maps

The temperature is indicated by a colour scale on the Meteosat image.