An isotherm refers to a line associating locations with equivalent temperatures. The isotherm maps demonstrate that where the temperatures are comparatively low and high, and also where temperature modifications are dramatic or gradual over a distance. The isotherms are demonstrated with curved lines or in colored bands associating the temperatures.
In the given case, one should go towards the South-West direction of the map to find a warmer temperature as the isothermal line of the highest temperature, that is, of 68 degree F directs towards the South-West.
