Hundreds of flights canceled as record-setting rain hits Chicago

(CNN) -- Airlines canceled hundreds of flights at Chicago's airports Thursday as record-setting rains pelted the Windy City.

More than 600 flights were canceled Thursday due to weather, the Chicago Department of Aviation said.

In a 24-hour span, Chicago has been deluged with nearly 7 inches of rain, the National Weather Service reported early Thursday afternoon -- and it isn't over yet. To put that in perspective, the city averages 3.38 inches of precipitation for the entire month of April.

A flash flood warning extends through 8 p.m. Thursday across Cook County, as well as several other counties in north central and northeast Illinois and northwest Indiana.

At Chicago O'Hare International Airport, airlines reported delays averaging 90 minutes or more for flights, and flooding forced the closure of a nearby road.

The flooding comes as a powerful spring storm that snarled air traffic in the Rockies and Midwest on Wednesday moves farther into the U.S. heartland, tormenting the region with everything from heavy snow to severe thunderstorms.

Wednesday was the sixth-wettest April day recorded at O'Hare. But that was just a taste: By 7 a.m., morning rain had already made Thursday the rainiest April day ever for Chicago.

"Emergency management reported that numerous roads and interstates were closed due to flooding," the weather service said. "Reports of stranded vehicles have also been relayed in addition to flooded homes and other buildings. Some municipalities have also declared states of emergency due to the flooding.

"Excessive runoff from this storm will cause flooding of small creeks and streams" and affect low-lying areas.

To that point, the north branch of the Chicago River at Albany Avenue set a record when it crested at 8.57 feet, smashing the record of 7.86 feet set in 2008, according to the U.S. Geological Survey.

American Airlines spokesman Matt Miller said severe weather is affecting its hubs not only in Chicago but in Dallas/Fort Worth. American and American Eagle have canceled 413 flights on Thursday because of weather, he said.

Southwest Airlines spokesman Chris Mainz cited delays and cancellations because of weather in Chicago and storms in other parts of the Midwest.

"We are operating, but it's slow going through Chicago right now," he said.

The weather service forecasts a moderate risk of severe weather from Arkansas and Mississippi to southern Michigan, but the full reach of the system stretches from Texas into Canada.

Airlines reported more than 200 cancellations at Denver International Airport on Wednesday after the storm system dumped up to 7 inches of snow in the area and much more in the mountains.

Flight delays at the Denver airport averaged just over two hours and 15 minutes on Wednesday afternoon, according to the Federal Aviation Administration.

And there would be no home runs flying out of Coors Field either, as snow prompted the postponement of Wednesday night's baseball game between the Colorado Rockies and New York Mets.

Parts of the state were under a blizzard warning before the storm moved to the east.

The weather system caused its share of trouble across the southern Plains.

Severe weather Wednesday evening damaged a Goodyear tire plant and other buildings around Lawton, Oklahoma, Comanche County Sheriff Kenny Stradley said. There were no immediate reports of injuries.

In California, firefighters are on high alert as gusty winds are expected to increase the fire danger across much of Southern California, the state's Department of Forestry and Fire Protection said Thursday.

The agency notes that the weather service issued a red flag warning starting Thursday and Friday because of moderate Santa Ana winds. The agency said gusty winds of up to 50 mph are expected across many parts of Orange, Riverside and San Diego counties. Manpower has been bulked up so crews can respond to wildfires, and air tankers will be staffed.

"Fire season may only be beginning, but the potential for damaging wildfires exists this year due to our dry winter," said Chief Ken Pimlott, the agency's director. "Everyone should be extra careful during this red flag warning and ensure they are ready for a wildfire."