I think it’s the same color as the color designation for:
Avg.: 72°F | 58°F
But I have no idea what the graph is showing if the blue line is showing the Temperature at that time of the day. All the values change with the vertical slider for to change the time of day.
If your brother uses trailcams it also importa their photos and GPS locations along with each pictures Metadata that includes temp, time, moon cycle and creates heat maps on your hunting property for when and where deer are depending on the variables you adjust. Cool way of figuring out like what food plots or feeding areas they go to when it’s hotter and shit like that. It never occurred to me that the deer were eating on top of the valley days it was cooler and ate down in the creek valley on warmer days until I saw the heat maps and made so much sense.