A perennially wet and at times stormy weekend fueled flooding concerns across the region and sparked the cancellation of one of Chicago’s newest and most unique fundraisers.

As of 1 p.m., many areas across Chicago had seen 2 to 3 inches of rain fall in the past 48 hours, according to the National Weather Service. Forecasters Sunday morning issued a hazardous weather outlook that noted thunderstorms as well as an elevated flooding risk and a swim risk for Lake Michigan beaches.

NWS meteorologist Zachary Yack said several waves of rain and thunderstorms had rolled through the area, including some torrential downpours in some areas.

“When we have rain of that magnitude, there’s a threat of localized flooding and rivers rising,” Yack said.

The Metropolitan Water Reclamation District of Greater Chicago issued an Overflow Action Day alert, asking people to limit water usage, because most Chicago area sewers carry combined sewage and stormwater, which can overflow during heavier periods of rainfall. The region’s massive Tunnel and Reservoir Plan – built to capture excess combined sewer water – was reporting rising levels at its reservoirs, with its southwest suburban McCook reservoir 95% full Sunday. With that reservoir being so full, the system reverted to releasing some combined storm and sewer water into local waterways starting about 5 a.m. Sunday, said MWRD Executive Director John Murray.

But levels were far lower for MWRD’s south suburban Thornton reservoir — the scene of record-breaking heights earlier this summer — which was reported at just 17% full.

The weather affected two major Sunday events in Chicago, canceling one and delaying the other.

Organizers of the Chicago River Swim announced on social media early Sunday that the event was canceled, citing weather and river conditions. The race, started last year, sees swimmers tackle the Chicago River’s main branch downtown to showcase the river’s cleanup while raising money for ALS, a fatal neurological disorder also known as Lou Gehrig’s disease.

Storms also led to the early closure of Riot Fest Saturday night and delayed its reopening until 2 p.m. Sunday, when much of the rain was expected to pass.

Yack said that, by Sunday afternoon, the bulk of the rain had passed through the area, with occasional light rain expected to end sometime Sunday night.

“For the most part, we’re looking at mostly a dry forecast heading into this week,” he said.

The NWS forecast a 20% chance of showers before 1 p.m. Monday on what is expected to be an otherwise cloudy and breezy day, with clouds breaking for some sun Tuesday, and both days seeing highs in the mid 60s.