Mr. Obama visited the Abraham Lincoln National Cemetery in far southwest suburban Elwood accompanied by Marines. He laid a wreath in memory of those lost in service to the nation.
However, storms moved into the area as the president prepared to speak and became more intense as he took to the podium.
" Excuse me. Everybody listen up. We are a little bit concerned about lightning. This may not be safe. I know all of you are here to commemorate the fallen. That's why we're here," Obama said. "What we'd like to do, if possible, is to have everybody move back to their cars."
The crowd dispersed as heavy rain fell.
Obama tried to wait out the storm in the cemetery's administration building. At one point he boarded a pair of buses to greet military families that came for the ceremony. Within the hour, however, reporters who accompanied the president to the cemetery were told that Obama would not be delivering the speech.
Bad weather persisted, and the event was cancelled.
"We were going to stay and see the president. We got rained out. The rain was terrible. It was really terrible. It turned out to be not a very good day," said Westley Johnson.
"We don't get this opportunity too often. So, we thought we would come out here and see our president, but it was a good time. It is kind of a rotten ending," Ryan Thompson told ABC7 Chicago.
Most visitors had to park at a remote lot miles away and take a shuttle bus to the cemetery. Also, most had been told they could not bring umbrellas. When it began to thunderstorm, the crowd of people waited to return to their cars.
Some were still waiting as late as 1 p.m.
Making the situation worse was the fact that some visitors were elderly or disabled. So, it was difficult to move everyone quickly.
Obama had spoken at the Lincoln cemetery in 2005 when he was a U.S. senator. Lincoln created the system of national cemeteries during the Civil War.
Upon leaving Elmwood, Mr. Obama and his family boarded Air Force One and returned to Washington in less than two hours.
After landing at Andrews Air Force base, the president spoke to troops about the troops who are no longer with us.
"Though our heart aches in their absence, we find comfort in knowing their legacy shines bright on the people they love," Obama said.
Then, the president thanked the soldiers personally as he greeted them.
(The Associated Press contributed to this report.)