Homographs are words that are spelled the same regardless of pronunciation (they may be pronounced the same or differently). Homonyms are words that are both spelled and pronounced the same. Therefore a homonym is both a type of homograph and a type of homophone. To be correct I believe the Venn diagram should have one circle labeled homograph and the other labeled homophone. The intersection should be labeled homonym.
An Excessive Heat Warning is issued when heat indices are expected to reach at least 105 degrees, except at least 110 degrees over Delmarva and far southern New Jersey (Salem, Cumberland, Cape May, and Atlantic Counties).
Both very cold and very hot temperatures could be dangerous to your health. Excessive exposure to heat is referred to as heat stress and excessive exposure to cold is referred to as cold stress. In a very hot environment, the most serious concern is heat stroke. In absence of immediate medical attention, heat stroke could be fatal. Heat stroke fatalities do occur every summer.