A low pressure area strengthened into Tropical Depression Ester early Friday, prompting state weather bureau Pagasa to raise Tropical Cyclone Wind Signal No. 1 over Batanes as conditions deteriorated.
The system was last tracked before dawn west of Itbayat, moving northeast at 20 kilometers per hour with maximum sustained winds of 45 kph and gusts reaching up to 55 kph.
Authorities warned residents in Batanes to brace for strong wind gusts and periods of heavy rain as the cyclone skirted the northern edge of the country.
Forecast models showed Ester heading toward Taiwan, with a possible landfall over its southern portion later in the day.
Weather officials said the tropical depression could exit the Philippine Area of Responsibility by Saturday morning if it maintains its speed and direction.
Even as Ester moved away, the southwest monsoon continued to enhance rainfall over western Luzon, bringing intermittent showers to areas including the Ilocos Region, Abra, Benguet, and Zambales.
Metro Manila and nearby provinces were also expected to experience cloudy skies with scattered rain showers and thunderstorms, while other parts of the country may see isolated afternoon rains.
Pagasa earlier declared the onset of the rainy season, signaling more frequent and widespread rainfall in the coming months, especially across western Luzon and parts of the Visayas.