Heavy rain Wednesday night caused a temporary closure of Interstate 43 on Milwaukee's south side and forced the Milwaukee Metropolitan Sewerage District to begin a forced combined sewer overflow at 8:30 p.m.
Local meteorologists estimated rainfall totals between two and four inches. Small hail was reported in parts of both Milwaukee and Waukesha counties.
The official flash flood warning for Milwaukee, Ozaukee and Waukesha Counties expired at 11 p.m., although high water remained on roadways and around creeks and streams. Communities across Wisconsin were still recovering from high winds and at least three confirmed tornadoes when rain began falling on saturated ground.
Gov. Tony Evers declared a state of emergency on Wednesday afternoon.
Here's what to know about impacts of Wednesday night's storm in Milwaukee:
Traffic: I-43 temporarily closed while flooding leaves Brewers fans trapped
Around 9 p.m., law enforcement closed lanes of I-43 between Holt Avenue and Becher Street due to flooding across the roadway. Traffic cameras showed vehicles stuck in standing water in the southbound lanes of I-43 as traffic was rerouted.
Two westbound lanes of Interstate 94 were also temporary closed at 25th Street due to flooding.
To the west, fans leaving American Family Field after the Brewers' win (over the Toronto Blue Jays) were met with bumper-to-bumper traffic and flooded roads, including Brewers Way. Half a dozen vehicles were stuck in standing water near the Frederick Miller Way overpass.
Traffic cameras showed crews clearing storm drains on Brewers Way while fire rescue checked on people who were standing on top of their vehicles around 9:45 p.m.
Back downtown, photos posted on social media showed street flooding on Brady Street that reached the top of vehicle tires.
Flooding also reached Marquette University's campus. Around 10:30 p.m., Marquette University Police asked students and community members to stay away from the intersection of West Kilbourn Avenue and North 15th Street due to flooding. The university also reported damage to some laundry facilities and water leaks in some campus buildings.
Water remained on the roadways around 9 a.m. Thursday morning, including at the intersection of 6th Street and Holt Avenue.
A swamped morning around Milwaukee as rainwater tries to drain.
— Kati Kokal (@katikokal) April 16, 2026
6th and Holt Avenue around 9am this morning. CC: @WUWMradio pic.twitter.com/pCeVvXKEqc
MMSD begins forced sewer overflow to deal with stormwater
Heavy rains throughout the evening Wednesday caused MMSD to begin a forced overflow of the combined sewer system.
The combined sewer system collects rainwater runoff, domestic sewage, and industrial wastewater into one pipe. Under normal conditions, that pipe transports all of the wastewater it collects to a sewage treatment plant for treatment, then discharges to a water body.
During a forced overflow, untreated stormwater and wastewater discharge directly to nearby streams, rivers, and other water bodies. Historically, these overflows have included releasing wastewater into Lake Michigan.
Combined sewer overflows contain untreated or partially treated human and industrial waste, toxic materials, and debris as well as stormwater.
Bus delays Thursday morning due to road flooding
The Milwaukee County Transit System announced likely detours and delays Thursday morning due to the severe weather.
Real-time bus tracking information can be found on RideMCTS.com or in the Umo app. MCTS also has a customer service line available after 8 a.m. at (414) 937-3218.
Flooding at Riverside University High School
Water in the basement of Riverside High School caused students to relocate to other classrooms in the building on Thursday, according to MPS Public Information Officer Stephen Davis.
Separately, smoke in the building at Rufus King High School required students and staff to relocate nearly a mile to the south to Andrew Douglas Middle School for the day Wednesday. The smoke was not caused by a fire or flooding, but by a "mechanical issue with an air handler in the school’s basement tunnel," according to a note sent to families by principal Doreen Badillo.
Power outages remain from Tuesday's high winds
We Energies reported scattered power outages throughout Wednesday evening impacting around 3,300 customers.
As of 11 p.m., the largest concentrated outage appeared to be affecting 80 customers in the Wauwatosa area. That outage began early Wednesday morning and was caused by wind damage from storms Tuesday night.
Milwaukee-area residents recall summer 2025 flooding in dealing with recent storms
In a social media post Wednesday morning, The Village in downtown Wauwatosa shared a video showing the Menomonee River rising higher than usual.
The post read "since we all have PTSD from last August, fingers crossed the next round of storms misses us," referencing the historic flooding that caused damage to wide swaths of the Milwaukee area in early August.
Wauwatosa was especially hard hit when up to 14 inches of rain fell in two days, according to data from MMSD released at the time.
Residents whose basements or cars flooded in that storm may now be better equipped to handle extreme weather. Or they could still be recovering from the expensive damage.
This story will be updated.
