The daily maximum temperature of steel materials installed outdoors was estimated using the daily maximum values of the outside air temperature and the amount of solar radiation. By making the following assumptions, it was possible to estimate with good accuracy with respect to the measured values. 1. The total heat transfer with the external environment is 0 (steady state). 2. Heat transfer to the external environment is performed through the polygonal outer surface that surrounds the member. 3. The temperature of each part of the member is uniform with the average temperature of the member.
