The 1900 agricultural season in Minnesota was challenging.
Following a dry early spring, crops were planted in dusty soil and suffered from both excess heat and a lack of rainfall. Most counties reported from 4 to 6 inches less than normal rainfall from May through July. As a result, hay harvest was light and small grain yield potential appeared to be quite modest. Then an abrupt and wholescale change in the weather pattern across Minnesota ensured for August.
Temperatures were consistently above-normal with high humidity, and the polar jet stream guided one frontal system after another across the state. Many of these frontal systems were embedded with heavy rainfall and severe thunderstorms. Fortunately, very few brought hail and high winds.
Both rainfall frequency and amount were unusually high. Some areas reported 16 to 17 days with rain during the month.
Over the Red River Valley and across west-central Minnesota, fully half of the days brought rainfall. In some areas, it rained on seven consecutive days from August 5-11. Many of these daily rainfalls ranged from 1 to 3 inches. Portions of Becker and Douglas Counties reported between 3 to 4 inches August 10. Many counties reported between 6 to 10 inches of rainfall for the month. Small grain harvests had to be delayed and there was no hay cut during the month.
Back then, drainage ditches were relatively few, so most fields were ponded. Even the statewide average rainfall for the month was nearly 7 inches, fully twice the normal.
Alexandria in Douglas County set an all-time record for the month of August in western Minnesota, with a rainfall total in August of 16.52 inches. That is a season’s worth of rain in one month.
Farmers hoped to salvage some harvest of crops during September, but the wet weather pattern that produced the state’s wettest August in history was stubborn and did not leave the state. Rainfall amounts were also twice as much as normal in September, with many counties reporting rainfall totals ranging from 5 to 7 inches.
September of 1900 ranks as the fourth wettest in state history with a statewide average of nearly 6 inches. Thus, the combination of August and September in 1900 delivered a statewide average rainfall of nearly 13 inches, the most in history. For perspective, consider that last year, regarded as very wet across the state in August and September, the statewide average was nearly 9.5 inches.
Four of the past five years have seen August and September deliver wetter-than-normal conditions across the state. It would not be a surprise to see such a pattern prevail again in 2020.