Temperature data available for Montcalm County show the following extremes; a high of 108 degrees F. on July 13, 1936 and a low of –25 degrees F. below zero on February 12, 1914; the warmest monthly mean temperature, 78.1 degrees F. was recorded July 1921, while the coldest was February 1936 with 13.3 degrees F. The average date of the last freezing temperature in the spring is May 9, while the average date of the first freezing temperature in the fall is October 3. The frost-free period or growing season averages 146 days annually.
The average annual precipitation for the county is 31.37 inches. This precipitation is well distributed throughout the year with the summer season, May to October, receiving an average of 17.53 inches or 56 percent of the average annual total. Summer precipitation is mainly in the form of afternoon showers and thunderstorms. Thunderstorms occur on an average of 39 days each year.
Average annual evaporation is 28 inches for the area. With average potential moisture evaporation during the summer season exceeding the average precipitation by 60 percent, soil moisture replenishment during the fall and winter months plays an important role in the success of agriculture and growth of forests in the area.
While drought may be periodically experienced, only 1 percent of the time will drought conditions reach extreme severity and adversely effect agriculture and forestry production.
Average annual snowfall for the area is 44.7 inches. However, snowfall totals more than 70 inches west of Greenville and closer to Lake Michigan. There is very little change in snowfall totals going eastward from Greenville. Heaviest one day total for snowfall is 12.0 inches, which occurred December 19, 1929.