Seniang is the 19th weather disturbance to hit the country this year.
Summit organizers hope it will leave the country before the summit starts on Monday.
Ten ASEAN heads of state and Japan Prime Minister Shinzo Abe, Russian President Vladimir Putin, and President Hu Jintao of China will start arriving on Saturday.
In its 5 p.m. bulletin yesterday, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said Seniang was spotted 1,010 kilometers east of Southern Leyte, packing winds of 55 kilometers per hour near the center and moving west at 19 kph.
Nathaniel Cruz, Pagasa director, said there is a possibility that Seniang will develop into a full-blown typhoon as it traverses the Visayas.
Seniang was forecast to be at 610 kms east of Southern Leyte this afternoon; 190 kms southeast of Guian, Eastern Samar by Saturday afternoon; and in the vicinity of Mactan, Cebu by Sunday afternoon.
The weather bureau has not yet raised public storm signal warnings, adding the disturbance is not likely to affect any part of the country within the next 24 hours.
Cruz said aside from global warming, El Niño in the western part of the Pacific Region is one reason why the country was hit with strong typhoons this year.
"One of the factors of strong typhoons is the warm sea surface level," he said.
The country is still recovering from the monstrous effect of super typhoon "Reming," which killed more than a thousand of people in Albay.
Pagasa said about 19 to 20 tropical cyclones usually hit the country a year, adding they cannot predict if Seniang would be the last to enter the Philippines this year.