Calmer winds may aid Colorado firefighters in epic battle FBI is investigating the cause of the wildfires Temperatures cool in Colorado, winds calm President Obama will visit the state on Friday The Denver Broncos donate $50,000 to relief efforts (CNN) -- Calming winds could help Colorado firefighters gain ground Thursday on an explosive wildfire that has devoured more than 15,500 acres and chased 36,000 people from their homes near Colorado Springs. The development would be welcome news to crews that have been battling erratic winds since early in the week. "We are learning as we fight this fire some of its tricks," said incident commander Rich Harvey. And one of its tricks is to run down these hills that way. You can fool us once, maybe, but not twice. Officials said they had not completed an inventory of homes and other structures lost or damaged by the Waldo Canyon Fire, which was only 5% contained late Wednesday. The rampaging blaze has captured Washington's attention, from the White House to the FBI. President Barack Obama will travel to the Colorado Springs area Friday to survey the damage and thank responders battling the blaze, the White House said. The Denver office of the FBI, meanwhile, has joined local authorities in investigating reports that the fire may have been set. "It infuriates me and it just makes my blood boil," Gov. John Hickenlooper said at the thought an arsonist may have started the fire. It creates a physical reaction in me ... to think that there's someone out there, because they get some kick ... there's some joy that they get (from setting a fire). The forecast in the coming days will be somewhat kinder to firefighters. Temperatures are expected to cool into the lower 90s with winds no more than 10 mph -- a far cry from the 65 mph gusts on Tuesday that whipped the flames through mountain canyons and past containment lines. The Waldo Canyon Fire captured attention because of its proximity to landmarks such as Pikes Peak and the Air Force Academy, and also to Colorado Springs, a city of about 400,000, the state's second largest. The inferno has been a challenge even for some of the country's best firefighters - sometimes getting the best of them. "We have rehearsed and practiced disasters," said Dave Rose, public information officer for El Paso County, which includes Colorado Springs. We have never seen one like this before. Some rain did fall Wednesday on a separate fire burning near Boulder, according to the National Weather Service, but the extended forecast calls for no more than a slight chance of precipitation. The bone-dry conditions may make the Fourth of July holiday less festive for many Coloradans. Fireworks displays in Jefferson and Douglas counties -- to the south and west of Denver -- have been canceled. With tens of thousands of state residents out of their homes, the Denver Broncos pledged $50,000 to relief efforts for the wildfires. "This is our home, and we need to do whatever we can to take care of our neighbors," team owner Pat Bowlen said. If at all possible, I encourage our fans to help however they can in providing relief during this time of need. Open Story: iReporters share their harrowing views of the western wildfires Richard Brown, the Colorado Springs fire chief, on Tuesday described the Waldo Canyon Fire as a "firestorm of epic proportions." Stan and Darlene Colbert were among the last families in the evacuation zone to pull out. They waited, hoping the fire would subside, but after watching the flames from their back porch, they knew it was time to go. The first things the couple -- married 43 years -- packed were the family photos. Every one of them I could find. Every photo because I can't replace those," said Darlene Colbert. The flames came dangerously close to the Air Force Academy's main campus, and an evacuation order was issued for about 700 residents in its Pine Valley Housing and 1,400 in Douglass Valley Housing, said public affairs officer John Van Winkle. The facility was closed to visitors Wednesday, with only essential personnel asked to report. The academy's Class of 2016 -- all 1,045 cadets -- is still scheduled to arrive Thursday, but officials are making contingency plans in case they have to report to a different location on the base. Rose, the county information officer, said one in four callers to the joint information center are offering food for firefighters, shelter for displaced neighbors or to volunteer in some capacity. "It is a somber resolve," Rose told CNN. There's no doubt that we have a grim reality that we have lost a number of structures. Our western border mountain vista has dramatically altered. Colorado wildfires had consumed 181,426 acres by Wednesday afternoon, according to the Colorado Division of Emergency Management. It was 75% contained late Wednesday. The total number of homes burned stood at 257. An estimated $33.5 million has been spent trying to contain the blaze. CNN's Jim Spellman contributed to this report.