On 7 October, a Low-Pressure Area East of Camarines Norte developed into a tropical depression while moving erratically over the Philippine Sea, and on the following day intensified into a Tropical Storm called Kompasu (locally known as Maring). On 10 October, Tropical Storm Kompasu merged with a Tropical Depression (locally known as Nando) and continued moving towards the Extreme Northern Luzon.

On 11 October, Tropical Storm Kompasu intensified into Severe Tropical Storm (STS) and passed close to south of Camiguin Island, after which it made a landfall in the vicinity of Fuga Island, Cagayan in Region II. It further enhanced the southwest monsoon, bringing more rain to already inundated areas and causing heavy flooding in Cagayan Valley, MIMAROPA and Cordillera Administrative Region (CAR). Although, the Severe Tropical Storm exited the Philippine Area of Responsibility (PAR) on Tuesday 12 October, further heavy rains were experienced.

National Disaster Risk Reduction and Management Council has reported a total of 235 flooded areas and 31 incidents of rain-induced landslides in Regions I, II, III, MIMAROPA, CARAGA and CAR. Flooding up to waist level has been caused by continuous rains and the high saturation of soil moisture. A total of 155,156 families or 611,705 persons affected in 1,380 barangays in Regions I, II, III, MIMAROPA, VI, CARAGA and CAR with 39 dead, 3 injured and 17 missing. At least 4,318 families or 15,130 persons are currently taking temporary shelter in 91 evacuation centres. (IFRC, 19 Oct 2021)