So MAYBE, and I'm pulling this out of my ass with no background here, but expectation is temperature doesn't jump, but flows as a gradient. Using France as the start, we've white fading to dark greys then reds, which is the hottest of the three white possibilities. As going hotter then that gets pink again, the top end is white in France. We then decrease down the scale until we get those. green pockets. Light green/white touching green would signify the lower of the three white temps. Not a great map, but perhaps it's an understood practice with the field. After all, how do you convert a quantitative scale into qualitative data. You can't really just number everything (people have shit attention spans and they'll gloss over immediately. Anybody who's delivered technical data to management can attest to that lol) Color works well for that, but has a limited useful spectrum. Getting too specific in a single spectrum muddies the graphic (what's the exact color over Lisbon here? This kinda salmony guy? So 8? Or closer to 9?)