South Bend Indiana Climate
South Bend is under the climatic influence of Lake Michigan with its nearest shore 20 miles to the northwest. The lake has a moderating effect on the temperature. Temperatures of 100 degrees or higher are rare and cold waves are less severe than at many locations at the same latitude. This results in favorable conditions for orchard and vegetable growth.
Based on the 1951-1980 period, the average first occurrence of 32 degrees Fahrenheit in the fall is October 18 and the average last occurrence in the spring is May 1.
Precipitation is fairly evenly distributed throughout the year with the greatest amounts during the growing season. The predominant snow season is from November through March, although there are also generally lighter amounts in October and April.
Winter is marked by considerable cloudiness and rather high humidity along
with frequent periods of snow. Heavy snowfalls, resulting from a cold
northwest wind passing over Lake Michigan are not uncommon.
THUNDERSTORMS: There in an average of 42 thunderstorm days per year at South Bend with most occurring from May to August. Measurable precipitation typically falls on 148 days of the year. Mid-winter through early spring is the wettest time of year, with autumn the driest.
TORNADOES: Tornadoes are not common but funnel clouds are sighted more regularly. Most tornadoes produce F0 to F1 damage with more devastating types rare. Northern Indiana was affected by both the 1965 Palm Sunday Outbreak and the 1974 Super Outbreak. Cold air funnels are not unusual...especially in the spring and fall.
WINTER WEATHER: Snowfall averages 81.8" per year...much of it from lake effect snow squalls. The greatest 24-hour snowfall was 17.5" November 25-26, 1977. The most likely month for heavy snow is January. The latest snow fell May 26 1961 and the earliest snow fell September 25 1942. Typically the last snow of the season is in mid-April with the first snow of the autumn around the first of November. 1977-78 was the snowiest season with 172.0", while the least snowy was 1948-49 with 23.2". Snow depth on the ground at any one time rarely exceeds 10". Freezing precipitation events are not uncommon but major storms are usually several years apart.
DENSE FOG: Dense fog is most common in the spring when warm air masses ride over melting snowpack. There are typically 23 days per year with fog reducing visibility to less than a quarter mile.
HIGH WINDS: High winds exceed 50 mph once or twice a year. The winds are usually associated with strong low pressure systems moving across the Great Lakes or up the Ohio River Valley. The highest wind gust on record is 92 mph August 22 1996. Prevailing wind for the year is 10.1 mph from the southwest.
HEAT: The average July temperature is 72.9. The all-time high is 104 June 25 1988. The all-time August high is 103 and in September it's 99. Cooling degree days average 728 per season. There is an average of 3 days equal to or above 90 in June, 4.8 in July, and 2.9 in August.
COLD: Winter temperatures reach their low in January with the average 23.3. Daytime highs average 30.4 and lows 16.1. Heating degree days average 6331 per season. The coldest temperature officially recorded is -22 January 20 1943.
FLASH FLOODS: Flash floods are not uncommon in late spring and summer. Serious flash floods are more rare. The all-time 24-hour rainfall record is 4.88" August 2-3, 1995.
FLOODS: Flooding occurs several times per year on area rivers but dangerously high floods that cause major damage and threats to life are not yearly events. The highest stage of the Saint Joseph River at South Bend was 10.9 feet March 15 1982 and January 6 1993, second highest was 10.7 feet February 24 1985.