The average temperature outside the blinds is lower than that inside. What is the reason?

The average temperature outside the blinds is higher than that inside. There are many reasons:

The louver is off the ground 1.5 meters, which avoids the influence of ground temperature.

Put it in an open place to ensure air circulation.

The box is painted white to reduce the radiant heat of sunlight.

Shutters themselves are ventilated, in short, in order to measure the real air temperature as much as possible. Paint the box white: reduce the radiant heat of sunlight.

Put it in a louver box: avoid direct sunlight, prevent wind and rain, and make the measured value closer to the accurate value.