The Highest (above left) and Lowest Temperature (above right) chart shows the maximum temperature for a period from 7:00 a.m. through 7:00 p.m. LST the previous day and the minimum temperature for the period from 7:00 p.m. LST the previous day through 8 a.m.

Source: https://www.wpc.ncep.noaa.gov/dailywxmap/explaination.html