Record low ice on the Great Lakes. Tornadoes in February. A soggy spring that morphed into deepening drought in the fall. 

2024 marked an unprecedented series of extreme weather events, and historic highs and lows in Wisconsin. In some way, every season was record-breaking.

These extremes are expected to get more frequent and dramatic because of climate change. And although some may like to think of Wisconsin as a “climate haven,” the effects are already being seen here, and last year offered just the latest evidence.

Wisconsin’s climate is becoming warmer and wetter. Across the state, temperatures have warmed about three degrees and rainfall has increased about five inches, or 17%, since 1950, according to the Wisconsin Initiative on Climate Change Impacts’ most recent report. 

The impacts aren’t just on the environment. They’re economic, too. According to a recent analysis by the Center for Public Integrity, extreme weather events will cost Wisconsin up to $16 billion over the next 15 years. 

The science is clear that climate change is driven by human activity, largely the use of fossil fuels, like coal, oil and gas. These fuels are responsible for 75% of greenhouse gas emissions, which capture heat and warm the planet.

Steve Vavrus, Wisconsin’s state climatologist, said looking at historical data it’s particularly striking how much warmer the state has become — a trend people may overlook because of year-to-year variability. Based on available data through the end of November, Vavrus said, last year could be Wisconsin’s warmest yet on record.

“It’s like we’re gradually warming up the stove, and we don’t really notice it’s happening,” he said.

Here’s a look back on the unprecedented year of record-breaking highs and lows.

More: Wisconsin is not bracing for a hurricane. But the messages sent by Helene, Milton are loud and clear.

Wisconsin recorded its warmest winter on record

Last winter was Wisconsin’s warmest-ever on record.

According to the Wisconsin State Climatology Office, December 2023 to February 2024 was the warmest winter in the state since it began keeping records in 1895. 

The average temperature across the state was 28.3 degrees — close to 10 degrees warmer than the typical average. The previous record was 26.1 degrees set in 2001 to 2002.

Wisconsin was not an outlier. The contiguous United States as a whole experienced its warmest winter on record.

Vavrus previously explained that the balmy temperatures were due to the longer-term warming trend with climate change as well as an El Niño event. 

More: Cold, snowy winters are part of Wisconsin’s identity. But are they a thing of the past?

Wisconsin’s first February tornado

Feb. 8 began sunny and unseasonably warm, with Milwaukee setting a record-high temperature for that date of 56 degrees. 

But that afternoon, storm clouds rolled in, setting the state up for a bizarre bout of severe weather. In the evening, the first-ever February tornadoes in recorded state history ripped across south-central Wisconsin, causing damage upwards of $2.4 million.

One tornado touched down in rural Green County. The other struck Evansville, in Rock County. 

It isn’t fully understood how climate change is affecting tornadoes, Vavrus said. But one expected outcome is a longer tornado season. They form when warm, humid air combines with wind shear — a change in wind speed or direction over a short distance. Warmer winter temperatures in Wisconsin mean those conditions could occur outside of the typical tornado season, May through August.

Evansville Mayor Dianne Duggan said there was “a lot of talk and head-shaking” about the timing of the tornado, which she said “is a climate change issue.” 

“I guess we just need to be on our toes all the time now,” she said. 

In total, Wisconsin experienced 45 tornadoes in 2024, the third-highest annual amount in state history.

More: Two tornadoes confirmed in Wisconsin, leaving extensive damage in rural Evansville

More: Wisconsin has seen far more tornadoes than average this year. Is climate change to blame?

Record-breaking ice season seen in Lakes Michigan, Superior

Average ice cover across all five Great Lakes from January to March was 4.3% — the lowest on record since scientists began recording it 50-plus years ago. 

Across the region, it was only the second time that the average ice cover did not reach 5%, with the first occurrence in 2012 of 4.8%, according to ice data from the National Oceanic and Atmospheric Administration. 

Individually, Lakes Michigan and Superior hit historic lows as well, with average daily ice cover at 4.4% and 2.6%, respectively. 

December is an especially important month when Arctic air should start to cool the lakes down, setting the stage for how much ice there will be, said Bryan Mroczka, a physical scientist with the Great Lakes Environmental Research Laboratory. December 2023 was Wisconsin’s warmest last month of the year on record, and the first time the state’s average temperature for the month was above freezing. 

Last year’s mid-January cold snap allowed some ice to build, which is when Lakes Michigan and Superior maxed out at about 18% and 12% ice cover, respectively.

Overall, ice cover in the Great Lakes has been declining for the past five decades due to climate change, while also swinging from near record highs to near record lows within a few years.

“We will still have those days where you bundle the kids up to go to the bus stop, but it’s the duration of these Arctic outbreaks — they’re in and out in a matter of days,” Mroczka said. “That keeps the ice from forming.”

The impacts of low ice cover are far-reaching, impacting ecosystem health, fisheries, recreation and infrastructure. For instance, ice tempers waves during storms, protecting the eggs of Great Lakes fish, like lake whitefish, which overwinter in nearshore areas. Ice can also protect coastal infrastructure and prevent shoreline flooding and erosion. 

In Madison, iconic lakes Mendota and Monona also had far fewer ice-covered days. Lake Monona froze over Jan. 15 and thawed Feb. 28, its shortest duration of ice cover in recorded history. Lake Mendota had ice cover for its second-shortest period in history.

Soggy spring, drought reversal, third wettest June on record

Wetter-than-normal spring conditions led to a dramatic reversal of the state’s yearlong drought that began in June 2023. 

In fact, it was Wisconsin’s third wettest June since scientists began keeping rainfall records in 1895, according to the National Oceanic and Atmospheric Administration. On average, the state saw 7.22 inches of rainfall, more than 2.5 inches higher than normal.

More: From drought to rain, Wisconsin had biggest one-year flip-flop from last June to this one

The heavy rainfall led to significant flooding and storm damage, especially in the northwestern and south-central parts of the state where communities received upwards of six inches of rain above normal. 

More local records were set across the state. For instance, Bayfield County had its wettest June on record, and La Crosse saw 24 days of rain that month, breaking the previous record of 22 days set in 1935 and 2013. As river levels rose, the Mississippi River in La Crosse set a flood stage record for the month of June at about 14.2 feet June 28.

More: Decades after it disappeared, wild rice is booming again on the upper Mississippi River

And while Milwaukeeans got to dry off in June — at least compared to the rest of the state — the city had its third wettest spring on record, according to Vavrus. 

Algae blooms crop up along Lake Superior’s shore

In a state beloved for its water resources, many wonder how algae blooms — particularly those that release harmful toxins — will proliferate in a warmer, wetter climate. 

In general, warming water temperatures are expected to increase the frequency of harmful algal blooms and their size, according to the U.S. Environmental Protection Agency. 

Wisconsin experts say the impact of climate change is not entirely clear, and that the behavior of each lake may differ. Still, there were atypical bloom events last year that may bear climate fingerprints. 

Across the state’s inland lakes in 2024, 253 blooms were reported as of early December, according to Gina LaLiberte, the DNR’s statewide harmful algal bloom coordinator. About three-fourths of the reported blooms contained cyanobacteria, which can release toxins.

Both the total number of reported blooms and the fraction that contained cyanobacteria are up from 2023, which saw 174 blooms with two-thirds containing the potentially harmful bacteria. That may be because people are more aware of how to report blooms, LaLiberte said. 

Last year, though, there were “definitely some reports from lakes where people say they’ve never seen the lake like this before,” she said, particularly in northern Wisconsin.

In those instances, she believes climate change may be at play.

Blue-green algae blooms are an emerging problem in Lake Superior, since the first sizable bloom was observed in 2012. 

Scientists attribute Lake Superior blooms to climate change, as the undeveloped lake lacks the usual ingredients for algae blooms, such as farm runoff. Lake Superior is the second fastest warming lake in the world.  

There were 11 reports of blooms last year along the shores of Lake Superior and within the St. Louis River Estuary wedged between Duluth, Minnesota and Superior, Wisconsin, according to Kait Reinl, a freshwater scientist at the Lake Superior National Estuarine Research Reserve.

Reinl said that some of the blooms last summer had toxins, but most were under the limits for drinking water and recreation. One bloom neared that limit. 

While algae blooms are not uncommon in the other Great Lakes, Reinl said Lake Superior should be held to a different standard.

“If we hold Lake Superior to the lowest common denominator, we have nowhere to go but down,” she said. 

More: Blue-green algae blooms, once unheard of in Lake Superior, are a sign that ‘things are changing’ experts say

More: As Lake Superior wetlands become more vulnerable, tribe fears cultural guideposts could slip away

A burst of heavy rains in June, and then long, hot, dry days

June’s heavy rains drove Wisconsin to its sixth-wettest summer on record. But that didn’t last long.

Summer vibes stretched on through September, with multiple cities setting records for the number of consecutive 80-degree days. Throughout the month, daily high temperatures were more than six degrees above normal. 

It was also exceedingly dry, aside from a powerful burst of rain Sept. 21. Less than 1.5 inches of rain fell across the state throughout the month.

It went down as the third-warmest and sixth-driest September on record in Wisconsin — a “really unusual” combination of extremes, Vavrus said. Since 1895, only 2% of months in Wisconsin have experienced a temperature extreme and a precipitation extreme. 

Unseasonably warm and dry conditions persisted in October. Madison and Green Bay both recorded 80-plus degree days Oct. 29, setting or breaking records for the latest 80-degree day of the year. At the end of the month, a third of the state was in severe drought and two-thirds was in moderate drought — the first time in the history of the U.S. Drought Monitor that Wisconsin was completely in drought. (That drought eased in the weeks since.)

More wildfires hit Wisconsin, and they started earlier

More than 1,100 wildfires burned roughly 2,500 acres in Wisconsin last year, about 260 more than the 10-year average. 

And wildfire season started early, because much of the state was snow-free by February. 

More: Wisconsin’s wildfire season is beginning fast, with risk above normal

Typically, fire season starts in the spring and goes south to north as different regions of the state warm up, said Catherine Koele, wildfire prevention specialist for the Wisconsin Department of Natural Resources. Last year, fires started in early February. 

“It feels like nothing is cookie-cutter anymore,” she said. 

The warm and dry fall raised wildfire risk again. Further, fires that happen under drought conditions take longer for crews to put out because they tend to smolder, Koele said. 

An Oct. 18 fire in Green Lake County was the state’s largest, Koele said, burning 646 acres. 

“We do have fires in the fall, but to have that size of fire, that’s a little unusual,” she said. 

By early December, the state had spent $1.1 million on fire suppression, compared to an annual average of $600,000. 

How can you do your part on climate change?

Scientists agree that the ultimate way to slow the impact of climate change is to limit fossil fuel emissions, which requires drastic steps taken by the worlds’ largest emitters, like the U.S. 

Climate anxiety — or feeling distressed about climate change — has become an ever-growing phenomenon, especially among young people. And taking steps as an individual can feel daunting.  

Here are a few steps that experts say people can take to help:

• Talk to friends and family members about climate change. Climate concern is more common than people think, and sharing it with others can build bridges. 
• Reach out to local, state and federal lawmakers.

• Use less energy in your home by reducing heating and cooling use; weatherizing; washing laundry with cold water; hanging clothes and linens to dry.

• Change energy sources where you can, like switching to LED light bulbs or electric appliances and vehicles.

• Talk to health providers about the ways climate change and extreme weather may impact health. Create a climate-health plan with your provider, including how to get to appointments or safeguard medications during extreme weather events that may cause power outages.

More: Caitlin Looby combines scientific expertise, love of outdoors to report on the Great Lakes

More: Great Lakes tribes’ knowledge of nature could be key to navigating climate change. Will enough people listen?

Caitlin Looby and Madeline Heim are Report for America corps member who writes about the environment. Caitlin Looby can be reached at clooby@gannett.com. Madeline Heim can be contacted at 920-996-7266 or mheim@gannett.com.

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