(CNN) -- Heavy snow and high winds have delayed climbers from carrying the Olympic flame to the top of the world's highest peak. Their window of opportunity is likely to close by the end of May, when annual monsoon rains normally arrive.
The flame rests in the advanced base camp at 6,400 meters (21,000 feet) above sea level, burning in a lantern designed to protect it from low-oxygen conditions of the high altitude. It was ignited from the main Olympic flame, which began a three-month trek through China Sunday following a global torch relay.
Chinese officials said at a Monday media briefing that winds gusts were measured up to 140 mph (225 km/h) on Everest's north slope, making a climb too treacherous to attempt. A snow storm buried camps erected along the route, an official said.
Secrecy kept journalists at the base camp from knowing when the climb to Everest's peak -- 8,850 meters (29,035 feet) above sea level -- might begin.
One official said the events were going according to plan, but he declined to elaborate on what the plan was.
Tight security surrounds the mountain to prevent any anti-Chinese and pro-Tibet protests.
A team of 50 climbers, staged since last month at the advanced base camp needs four to six days of good weather to reach the summit and return down the mountain, one official said.
Despite the secrecy ahead of the effort, elaborate technical plans are in place so that China's official television network -- CCTV -- can broadcast the ascent live. A camera is expected to follow the flame to the peak, if all goes as planned.