On September 26, the Japan Meteorological Agency (JMA) started to monitor a weak tropical depression that had developed about 1,260 km (785 mi) to the northwest of Manila in the Philippines.

[1] During that day, while the depression moved towards the northwest its low level circulation centre rapidly consolidated in an area of favourable conditions for further development of the system.

[7] On the morning of September 29, the JTWC reported that Nalgae developed a small microwave eye like feature and multiple convective bands wrapped tightly into the center.

[10] Continuing on its quick westward run, Nalgae developed a tiny 5 nautical miles (9.3 km; 5.8 mi) eye with a small break in the eyewall around the eastern periphery, because of a slight vertical wind shear as estimated by the JTWC.

[11] On September 30, the Americans living in Philippines were reminded by the United States government "to carry their travel documents at all times and secure them in a safe and waterproof location."

The agency asked all the tourists heading to typhoon-hit provinces to remain flexible with their itineraries as several air and ship may be either cancelled or indefinitely delayed when the typhoon comes ashore.

[16][17][clarification needed] Nalgae, the second typhoon hit Philippines within one week made landfall along the coast of Dinapigue town in Isabela province.

"[18] The National Disaster Risk Reduction and Management Council director Benito Ramos said that thousands of rescue workers were deployed across Luzon and the island's sparsely populated northeast coast was evacuated following the orders from the president Benigno Aquino III.

[20] The governor of Isabela province, Faustino Dy said that "Hundreds of people in coastal areas had been evacuated as rain and strong cut power lines, uprooted trees and blocked roads with debris."

He added that "Nalgae could cause floods on Luzon's central plains before passing through La Union province, a tobacco-growing area, and then heading off into the South China Sea."

Also, the PAGASA announced that an estimated 10–18 mm per hour of rains were experienced in several areas across the nation filling up dams and causing river systems to swell.

[21] As the storm continued to move inland with strong winds, many structures including billboards, tarpaulins and wooden materials in the town of Cauayan were damaged.

[26] The extremely strong winds blown by Nalgae set off a rockslide in northern Bontoc provincecausing boulders to roll down a mountainside and smash on a passing van, killing one man.

The Rescue workers scrambled through the floodwaters on October 2, so that they could be able to deliver food, water and other relief materials to hundreds of villagers stuck on rooftops since several days after the twin typhoons ravaged the nation.

Seven towns north of Manila including Calumpit in rice-growing Bulacan province continued to be under waist-high waters after the rains brought by Nalgae, the 17th tropical cyclone to affect the disaster-prone nation in 2011.

[30][31] On October 3, Philippine authorities rushed aid to thousands of people marooned in their flooded homes for a week since Nesat and Nalgae together battered the nation.

one of the worst hit towns, a construction worker in line for receiving the relief materials said to a new agency, "We have no food to eat, and no clean drinking water.

The local weather agency announced that the water levels on the tributaries of major central Luzon rivers were still continuing to rise fast and posed a threat to the nearby towns and villages.