Idea of Heat Map Icon
It is a logo of a heat map. there is a 90 degree right angle located at the bottom left and inside the right angle are various sizes of circles. Some circles small some big. The bigger the circles are it is indicating the higher in temperature the heat is.
This page shows the different variations of the Heat Map from an Icons8 icon pack. Feel free to resize and recolor the icon, and then download the icon in PNG format for free.