One hundred years ago during another La Niña winter, Minnesota experienced one of the coldest months of January in history. If you recall, a La Niña winter brings cooler-than-normal sea surface temperatures in the equatorial Pacific Ocean.

This followed a bitterly cold month of December 1917 when temperatures averaged 9 to 13 degrees F below normal, and livestock producers were selling off as a result of lack of feed due to a poor growing season.

January 1918 began on the mild side, with temperatures 6 to 9 degrees F warmer than normal. Many observers reported daytime highs in the 30s and 40s. In some western Minnesota counties, it was as warm as 45 degrees F (Canby and Luverne). Farmers used the mild days to spread manure on their harvested fields.

A sharp turn in the weather pattern occurred during the second week of January, with a winter storm over Jan. 5-6 bringing mixed precipitation of rain, sleet and snow. Following this storm, temperature values plummeted, with the onset of an Arctic air mass out of the north.

Colder than -40 degrees F
The weather pattern across Minnesota over Jan. 7-31 was then dominated by northwest winds and extreme cold. Over this time period, temperatures average 12 to 15 degrees F cooler than normal, and more than a dozen climate stations reported a minimum temperature colder than -40 degrees F.

The state low for the month occurred at Warroad in Roseau County with a reading of -49 degrees F on the Jan. 26. As far south as Waseca and St Peter, it was as cold as -35 degrees F and -36 degrees F, respectively.

Both Worthington and Albert Lea reported 22 mornings with subzero temperature readings, and on many days the afternoon high temperature remained below zero degrees F as well.

Maintaining enough firewood and heating fuel was a challenge for many Minnesota residents, as the combined months of December and January in 1917-18 were the coldest in state history, averaging 12 to 14 degrees F colder than normal.

The prolonged Arctic cold during January had some significant impact on agriculture. Thin or little snow cover prevailed around much of western and southwestern Minnesota, so forage grasses and alfalfa in those regions of the state had little protection from the cold temperatures. In some counties, winter injury and even winterkill were common as a result of the very prolonged cold snap.

No reliable record of soil temperatures was kept at that time, but we do know than on some days of January 1918, the temperature remained below zero degrees F all day, and frost depths in the soil were extreme. Those who worked in graveyards reported the ground was frozen to at least 6 feet.

Seeley is University of Minnesota’s Extension climatologist.