isohyet

/ˈaɪsəhaɪɪt/
noun
  1. A line on a map connecting places that receive the same amount of rainfall.
    • Meteorologists drew an isohyet to show where the drought was most severe.
    • The isohyet for 40 inches of rain runs through the middle of the region.
    • By looking at the isohyets, you can see which parts of the country are wettest.