Install a 36" fan with a special fan track approximately 2 feet from ther louvers around the official white weather temperature box . The fan needs to be turned on when the nights are clear or partly cloudy and when the wind drops below 5 mph. This is important because radiational cooling frequently causes the minimum tmperature readings to be several degrees too low (below the air temperature) on clear calm nights. If a fan is used, the radiational cooling effects will be less than 1/2 of a degree rather than several degrees. Also, the fan needs to be used on calm sunny days where the temperature in the box may be a degree or two higher than the true air temperature. The official low temperatures are sometimes several degrees too low on calm nights or early morning at the Greater Cincinnati Airport in Northern Kentucky because radiational cooling by black body radiation lowers the temperature in the box a few degrees below the air if there is little or no wind. A white box still has a black body emissitivy of 0.90. This is why a fan is needed to exhaust air from a side on the offical temperature box so air flows ready through the box.