The president's visit to the Scout Jamboree at Fort A.P. Hill - which was supposed to happen Wednesday - was postponed because of severe thunderstorms and strong wind. President Bush is now scheduled to visit the gathering on Thursday evening.
But before the president's appearance was called off, many Scouts fell ill from temperatures that rose into the upper 90s, made worse by high humidity.
Half of those were treated at the base hospital, about three miles from the event arena, and released. Some 31 others were sent to other hospitals, where they are listed in stable condition, according to Jamboree spokesman Gregg Shields.
'We will continue to reinforce to everybody that they need to drink water and stay hydrated during the day," said Shields, urging Jamboree participants to take regular breaks in shady areas and stay cool.
Soldiers carried Boy Scouts on stretchers to the base hospital, and others were airlifted from the event.
Jamboree officials called for emergency help from surrounding areas, and ambulances transported Scouts during the storm, which brought high winds and lightning.
Jamboree spokeswoman Renee Fairrer said she was not sure if any of the illnesses are serious. "If there are any, I haven't heard about them yet," Fairrer said.
Hours earlier, Scouts began gathering for the event, passing through security screening to get a place in an open field facing the stage where the president planned to speak.
Scout leaders distributed water by the caseload, and the Scouts were told they could remove their uniform shirts if they had another shirt underneath.
"This is hot for me," said Chad McDowell, 16, who lives in Warrenton, Ore. "Where I'm from if it's 75, we think that it's a heat wave."
Those who fell ill suffered from dehydration, lightheadedness and fatigue, among other symptoms.
The gathering has drawn more than 40,000 Scouting enthusiasts from around the world to the fort about an hour south of the nation's capital.
The memorial service had been planned to honor four men who were electrocuted Monday while pitching a dining tent at the Jamboree.
On Wednesday, a spokesman said the group had ignored scouting guidelines by putting the tent under a power line.
The Scout leaders also had taken the "somewhat unusual" step of hiring a contractor to help with the task, Scouts spokesman Gregg Shields said.
"Boy Scouts are taught not to put their tents under trees or under power lines. I don't know what happened in that case," Shields said.