July frost in Ohio? Endangered species or already extinct?

As I explained yesterday, I created this blog to document changes in the climate of Ohio and surrounding areas. The purpose is not to advocate for or against action on climate change, or even to suggest that the changes are due to (or solely caused by) the actions of man. Instead, I hoped to call attention to documentary evidence that the climate of the state IS changing. The changes hitherto have been rather small, almost imperceptible over a human lifetime. Nevertheless, over time, the effects of the changing climate are discernible.

One of the more noteworthy (and, arguably, positive) effects of climate change has been an apparent lengthening in growing season. The longer growing seasons are primarily due to the increase in minimum overnight temperatures. The first frost of the fall has been gradually shifting later in the year, while the last frost of the spring has been gradually shifting to earlier dates. Most people today would scoff at the notion that frosts were once a common occurrence in parts of Ohio in the month of July. Today, temperatures seldom drop below the middle 40s anywhere in the state in most Julys. The most recent July cold snaps of note occurred in 1988 & 2001. Both years saw temperatures plummet into the upper 30s and lower 40s in outlying areas early in the month. But the climate wasn’t always so mild.

In the 1880s, the Weather Bureau began publishing state climatological reports. These reports provide a record for some of the changes in the climate system. One of the more striking observations from that foregone era was the occasional July frost. In several of the early years, observers reported light frosts in July. Frosty conditions were reported most frequently in inland northeast Ohio, the far northwest corner (near Wauseon), and in the north central hills (near Ashland and Mansfield). On a couple of occasions, damage was even reported to crops from July frosts. Needless to say, such an event would be highly unusual today. In fact, today, July frosts seem to be a rarity even in the far north lands (such as northern Minnesota, Wisconsin, and Michigan and northern New England).

Below, I’ve attached screen captures from the Climatological Data reports taken from the NCDC archives. The frosts of July 1890 and July 1891 were both accompanied by reports of isolated crop damage. But these were not the only years in which frosts reportedly occurred in July. Several other years also included reports of frosts and temperatures as low as 34.

Figure 1: July 1890 Ohio Climate & Crop Report. Light frost occurred at Garrettsville, Orangeville, Lordstown, Marion and Wauseon on the 21st; Youngstown reports a heavy frost on the same date, a few miles north of that place with considerable damage to corn and potatoes.

Figure 2: July 1890 Ohio Climate & Crop Report. The minimum temperature, 41, on the 27th, at Wauseon, was accompanied by a light hoar frost. Wauseon and Montpelier reporting tender plants damaged slightly by frost in the early morning.

Figure 3. July 1907 Ohio Monthly Weather Review, page 2. Unseasonably cool weather prevailed on the 3d and 4th, when temperatures of 40° or below were recorded at many of the northern stations. Frost was observed at Cleveland, Medina, Oberlin, and Wellington, and ice was reported on a bridge near South Lorain on the morning of the 3d. Lower temperatures in July have been recorded in the State only twice during the past 25 years.


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Just an ordinary guy with a penchant for the weather and climate!

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