We often look for shady spots during hot summer days for relief from the scorching sun. But did you know that shade doesn't make temperatures cooler. In fact, air temperature is actually the same in the sun or shade. It's solar radiation hitting our bodies which makes it feel hotter. On average, solar radiation makes the air feel 10-15 degrees warmer than it actually is.
This is why official air temperature is always measured in the shade. If the thermometer were placed in the sun, the solar radiation would heat up the thermometer and the resulting temperature would be measuring the warmed up thermometer and not the air around the thermometer.
Other factors that can affect temperature readings are placement of thermometers. Paved surfaces give off heat from absorbed solar radiation and will cause temperatures to be hotter so it's best to place thermometers over grassy surfaces. Also, good air flow is needed to get an accurate air temperature reading. Placing the thermometer 4 to 6 feet above the ground will prevent ambient ground temperature from affecting the reading.