The depression remained weak and was downgraded to a low pressure area later that day by the Japan Meteorological Agency (JMA) and after drifting through extremely favorable conditions, it intensified the next day and was categorized as Tropical Depression by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) and was given the name Ondoy after entering the Philippine Area of Responsibility. The Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert on the depression. It was then upgraded to a tropical depression by the JMA later that morning before the JTWC followed suit early on September 25, designating the depression as 17W.