A remarkable late-season snowstorm dumped 6” on Stockwell & Lafayette on April 16, 1870. 6" was also reported at Terre Haute & Indianapolis, as well as New Albany & Richmond. Vincennes also reported 6". 3” was measured at Rensselaer.
Rensselaer weather records show that the morning low was 30 degrees with that 3” of snow, but it was 49 with sunshine by 2 p.m. with much of the snow gone. The remainder of the month was very dry & warm.
Several inches of snow were reported in western Tennessee on the morning of April 16 (Sunday). It was reportedly the latest substantial snowfall so late in the season, seen in decades. By Wednesday, it was reported that it was so warming folks could be outside barefoot.
Rensselaer was at 82 degrees on April 23 at 2 p.m.
"No less than 6 inches" of wet, heavy, gloppy snow fell at Evansville, reportedly on trees with unfurling leaves & peach trees with leaves & flowers. However, temperature reportedly reached 44 the day after at noon & 54 for a final high temperature. The snow occurred with a 38 the day prior & 33 at night with the heaviest snowfall.
At Cairo, Illinois, it was reported that no original settler remembered such a snow so late. 4" fell there. "The oldest inhabitants" reported a "slight snowstorm and freeze on the 5th day of April, thirteen years prior, and during the four or five days next ensuing temperature remained at, or very near the freezing point, that year there was scarcely a peach, cherry or plum raised in Egypt (that area at the southern tip of Illinois is often referred to as 'Little Egypt'".
This would have been 1857, not 1858. 1857 was, by far, the coldest April on record of any location in Illinois or Indiana back to 1820, per primitive records. Contrastingly, 1857 saw one of the warmest Februarys on record after a brutal December & January, but that April & May were exceptionally cold. On June 11, the Black Walnuts had still not leafed out fully near Richmond, Indiana, nor had the American Sycamores (though they may have been a victim of blight, as the leaves die off & fall from this fungal infection when it is too cold & wet & then fully re-leaf by mid-June). The Black Locust trees were reportedly still quite bare May 24. The forests did not reach full leaf until the middle of June.
The latest occurrence of snowflakes on record in Greater Lafayette was May 18, 1857.
In the 1870 unseasonable snowstorm, it was reported that the "snowstorm prevailed through Illinois" and "snowstorm was generally prevailing throughout the State [of Indiana]."
St. Louis press reported on April 17: "Snow has fallen all day, and the storm continues with increased violence tonight."
"Heavy fall since Saturday morning, and at points north and west and as far as can be reached by wires."
2" of snow was reported in downtown Louisville, Kentucky; Wheeling, West Virginia saw a "cold, drizzling rain set in" Saturday evening.
Cincinnati, Ohio reported mainly just rain & just a bit of snow, but no accumulation. Press report remarked that "it was very cold".
Charles Goodwin, Superintendent of Gas Works for Memphis, Tennessee at the time wrote, "I rained yesterday at intervals and was very cold & disagreeable. A heavy snow fell toward night. Business on the levee was only moderately active." He also remarked that the Mississippi River was just a foot below the high water mark of the 1867 flood. Winter 1867 also saw a big flood on the Wabash River, as well, ranking in the top 10 highest levels on record (back to 1828).
Northeastern Arkansas reported "rain, sleet and snow".
"An easterly storm" of "wind & rain" was reported at New York City.
A "heavy rainstorm with thunder & lightning" in the evening was reported at Philadelphia.
"A heavy northeast storm" was reported at Fort Monroe, Virginia.
Flooding rainfall was reported across much of South Carolina.
A tornado was reported near New Orleans, Louisiana.
Several days prior to this storm, 24" of new snow fell in the Sierra Nevada, apparently the same storm system.
However, a major t'storm hit near Orangeburg, South Carolina with a "violent" hailstorm with stones to 2" in diameter that drifted up to 5" deep in the heavy rainfall just as our snowfall was winding down.
There was warmth prior to this snowfall after the rough winter, however. Winona, Minnesota was in the midst of major river flooding as the very deep snow pack was in melt around April 16 & peaches reportedly blossomed in late March in far southern Indiana with early warmth.
While the April 17, 1926 event dumped 6.5" of snow at Lafayette, that event appears to have been very much like the 2018 Easter snow with 6" in Greater Lafayette. However, the 1870 snow appears to have had a low pressure that came northward from the Deep South. This is what led to the several inches of snowfall even in Tennessee.
On the flip-side, it turned hot in early May.
According Rensselaer daily weather records for May 1870 & fragmented records at Lafayette, the 2nd began a long period of warmth & dry weather with 16 of 31 days in the mid 80s to around 90. Of these, three days were in the 90s at Lafayette & Rensselaer. Rensselaer was 92 at 2 p.m. on May 22. Lafayette hit 94 degrees. The lowest temperature of the month was 47 on May 12 at Rensselaer. Mean temperature for the month was 66-70 degrees area-wide.
At Rensselaer, it was at least 85 degrees each day May 2-5, May 14-18, May 20-22 & May 29-31. 1870 is still easily the hottest May on record for parts of the area, even beating the hot Mays of 1839, 1911, 1976 & 2012.
Here was a take regarding the snow at Chicago:
April 17, 1926 (& similar Easter 2018 snowfall) from clipper-type system & very strong frontagenetical forcing.
April 1-2, 2018:
April 15-17, 1870 reconstructed map based on surface data: