Fond du Lac has the typical continental climate of interior North America with a large annual temperature range and frequent short period temperature changes. Temperature extremes range from an all-time high of 107 degrees which was observed on July 14th, 1936 to a record low of -37 degrees fahrenheit, which occurred on January 30th, 1951. Winter temperatures (Dec-Feb) average near 20 degrees and summer temperatures (Jun-Aug) average in the upper 60s. Daily temperatures average below 32 degrees about 120 days and above 40 degrees about 210 days of the year. Fond du Lac lakes are normally frozen from mid- December to early April.
Fond du Lac lies in the path of the frequent cyclones and anticyclones which move eastward over this area during fall, winter and spring. In summer, the cyclones tend to pass farther north. The most frequent air masses are of polar origin. Occasional outbreaks of artic air affect the area during the winter months. Although northward moving tropical air masses contribute considerable cloudiness and precipitation, the true Gulf air mass does not reach this area in winter, and only occasionally at other seasons. Summers are pleasant, with only occasional periods of extreme heat or high humidity.
There are no dry and wet seasons, but about 60 percent of the annual
precipitation falls in the five months of May through September. Cold season precipitation is lighter, but lasts longer. Soil moisture is usually adequate in the first part of the growing season. During July, August and September, the crops depend on current rainfall, which is mostly from thunderstorms and tends to be erratic and variable. Average occurance of thunderstorms is just under 7 days per month during this period. March and November are the windiest months.
The ground is covered with 1 inch or more of snow about 60 percent of the time from December through February in an average winter. The soil is usually frozen from the first of December through most of March with an average frost penetration of 25 to 30 inches. The growing season averages 175 days.
Farming is diversified with the main emphasis on dairy farming. Field crops are mainly corn, oats, clover, and alfalfa. Fruits are mainly apples, strawberries, and raspberries.