Fewer hot days, with a wet start and dry finish to the season
by the WISCONSIN STATE CLIMATOLOGY OFFICE
This year’s meteorological summer (June through August) featured temperatures very close to normal throughout Wisconsin and Door County (where referenced in this summary, Door County climate data are from the Sturgeon Bay observation station). Hot weather was brief and – except for a late-August heat wave – not especially intense, a far cry from the near record-breaking heat across much of the U.S. this summer.
For example, in a typical year there are 10 days of at least 90 degrees at Wisconsin’s first-order weather stations (Eau Claire, Green Bay, La Crosse, Madison, Milwaukee, and Wausau), a frequency that’s been remarkably consistent for many decades despite the warming climate. By the end of summer this year, only six such hot days occurred and no such hot days in Door County.
The absence of triple-digit heat is something that has become surprisingly common in recent years, even though Wisconsin’s annual maximum temperature used to regularly surpass 100 degrees, based on data back to the 1880s. This year’s statewide summer average temperature was 67.3 degrees, slightly warmer than Sturgeon Bay’s average of 66.56 degrees.
The summer was also relatively quiet in terms of severe weather. Although this year has appeared active in terms of the number of tornadoes, the 21 confirmed tornadoes for summer 2024 tied 1967 for 15th place, well behind the 58 tornadoes that slammed the state in the summer of 2005. Of the 21 tornadoes this summer, half were weak EF0s, underscoring the unexceptional severe weather this summer. Furthermore, none of the summer tornadoes struck Door County, making the May 21 EF1 tornado that hit Washington Island the only tornado in the county so far this year.
However, much of Wisconsin did not have it easy due to an abundance of summer precipitation. Intense downpours resulted in rainfall rates of 1-2 inches per hour and extreme one- and two-day precipitation events the weekend of June 21 across many counties from Sauk to Sheboygan.
While Door County did not see the deluge that western Wisconsin experienced that remarkable weekend in June, the Cape Cod of the Midwest had its own memorable couple of days. Several rounds of thunderstorms, some severe, struck the area June 20 and 25. Reportedly, 1.57 inches and 2.8 inches fell on June 20 and 25, respectively, at the Sturgeon Bay site. Heavy rains also caused a new June water level record along the Mississippi River at La Crosse and broke Madison’s one-hour accumulation record on July 14. Unfortunately, by the end of the summer, dryness emerged in Door County and all of northeastern Wisconsin (and intensified in September). The summer ended with a statewide average of 15.73 inches, a noteworthy 3.09 inches above normal and the sixth wettest summer on record. For Sturgeon Bay and similarly for greater Door County, this summer brought 10.85 inches of rain, 0.16 inches below normal.
The abundance of rainfall the first half of the summer made for difficult working and growing conditions for agriculture. Cherry growers in Door County had a rough season, as noted by Rebecca Wiepz, the superintendent of the UW–Madison’s Peninsular Agricultural Research Station in Door County. In addition to the pests and disease caused by the mild winter and warm, wet spring, the repetitive rains during June and early July made it nearly impossible to protect crops from pests and the excess moisture promoted bacterial and fungal growth. Many growers were unable to harvest fields that they found to be infested. Amazingly, of the almost 15 million pounds of cherries harvested, only 500,000 pounds were rejected, which is impressive given the conditions.
The Wisconsin State Climatology Office (SCO) – a combined effort between UW–Madison’s Nelson Institute, Division of Extension, and Department of Atmospheric and Oceanic Sciences – helps all Wisconsinites use weather and climate data effectively. As a part of the UW’s larger Rural Partnerships Institute, the SCO focuses a large portion of its efforts to Wisconsin’s agricultural communities beyond Dane County, offering tailored tools like drought monitoring for crop management, divisional climate data and monthly climate summaries. Learn more and join the email list at climatology.nelson.wisc.edu.
