Retro thermometers that show temperature and advertises messages of various products ranging from soda bottle, clock, light fixture, gas station in style is referred as antique thermometer. It is also known as advertising thermometer as it advertises product on it.

This type of thermometers appeared in 1900s and by 1920s it was extensively displayed in United States by advertisers to advertise their products mainly in places where people gather like local general store, cafe, gas stations etc. The very early ones were made of metals and wood as these were intended to be hung outside. Later porcelain was also used. As it was mainly used for advertising, their sizes varied. Now, with the passage of time, these vintage thermometers are very much in demand. If it is still in working condition, it is highly valuable. However, collectors should be look out for wear and tear that would have occurred if it used or displayed for many years as claimed. Otherwise, it may be just a replica of the original.