The Weather Eye was a trade name for a Nash Motors

Nash Motors

Also see: Kelvinator and American Motors CorporationNash Motors was an automobile manufacturer based in Kenosha, Wisconsin, in the United States from 1916 to 1938. From 1938 to 1954, Nash was the automotive division of the Nash-Kelvinator Corporation...

-designed fresh-air automotive heating and ventilating system first used in 1938. This "Conditioned Air System" is characterized by a cowl-mounted outside air receiver that then passes fresh air through a heater core utilizing hot engine coolant for a heat source. In 1939, Nash added a thermostat to its Conditioned Air System, and thus the famous Nash heater was first marketed as the Weather Eye. Nash sales literature said that the thermostat's "mechanical eye" watched the weather, hence the name. The use of the Weather Eye name for automobile heating and air conditioning

Air conditioning

An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...

 systems continued in American Motors

American Motors

American Motors Corporation was an American automobile company formed by the 1954 merger of Nash-Kelvinator Corporation and Hudson Motor Car Company. At the time, it was the largest corporate merger in U.S. history.George W...

 (AMC) vehicles.

The famed "Weather Eye" was developed concurrently with the much lesser-known but contemporary Hupmobile

Hupmobile

The Hupmobile was an automobile built from 1909 through 1940 by the Hupp Motor Company, which was located at 345 Bellevue Avenue in Detroit, Michigan. Its first car, the Model 20, was introduced to the public at the Detroit Auto Show in February 1909...

 Evanair-Conditioner

Evanair-Conditioner

The 1938 Hupmobile Evanair-Conditioner, with the concurrent Nash Weather Eye , were the automobile industry's first fresh-air hot water heating systems...

 that took its fresh air through special hood scoop

Hood scoop

A bonnet/hood scoop is an upraised component on the hood of an automobile that either allows a flow of air to directly enter the engine compartment, or appears to do so. It has only one opening and is closed on all other sides...

s. The principles of both the Hupmobile Evanair-Conditioner and the Nash Weather Eye are still in use today in nearly every motor vehicle.

Other uses

The phrase "to keep a weather eye" on something, means to maintain a background awareness of something; to remain alert to changes without it occupying your full attention. The term is nautical, originating from seamanship

Seamanship

Seamanship is the art of operating a ship or boat.It involves a knowledge of a variety of topics and development of specialised skills including: navigation and international maritime law; weather, meteorology and forecasting; watchstanding; ship-handling and small boat handling; operation of deck...

.