tl;dr This is a USA map to visualize average or min-max temperatures for areas roughly the diameter of Chicago. It colors the tiles based on the proportion of the selected interval (annual or a specific month). The data is from a US agency [0]. This way, you can see that Los Angeles, CA is 40-80° F 75% of the year and Salt Lake City, UT is in that range only 10%.

[0] https://www.ncei.noaa.gov/products/land-based-station/us-cli...