On July 15, the system was enhanced to a tropical depression. At 11 pm, the Philippine Atmospheric Geophysical and Astronomical Services Administration issued the No. 1 storm signal to the northern part of Isabela Province, Cagayan Province and the Bataan Islands. As Denas continued to approach Luzon, the Philippine Atmospheric Geophysical and Astronomical Services Administration issued a second storm signal to the northern part of Cagayan Province at 5 pm on the 16th. 