Trego's Mountain Ear

Sir Thomas Allbutt invented the medical thermometer in 1867. The first attempts to use medical thermometers to analyze weather (that I have found) were physicians with Crook’s 1876 campaign following the Little Bighorn. Decent instruments, but misused – as I recall they were reporting sub-zero temperatures in September. The first use of a thermometer in Montana was with the Lewis & Clark expedition – they recorded temperatures daily until September of 1805, when the last of their three thermometers broke.

Around 1900, thermometers started moving into homes and yards – usually advertising thermometers. By 1920, measuring the day’s temperature became fairly common, even in the rural parts of the US. The difficulty of developing, then spreading thermometers across the nation is why our climate and weather data is, in general terms, recent.

We have long-term dating for first and last frosts – but you can tell if you have had a frost by watching your garden and a calendar. The first thermometers were developed in the 1600’s – but it took several centuries to refine the concept and get them in common use. By the 1890s, they were common enough to be showing up in some of our agricultural records – but other areas just show the first and last killing frosts of the year.