On the same day, the United States Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert (TCFA) on the consolidating depression.

After making its last landfall over Palawan, Rai continued to weaken before unexpectedly re-intensifying into a Category 5-equivalent typhoon by December 18, while nearing Vietnam.

At 06:00 UTC on December 9, the Joint Typhoon Warning Center (JTWC) started to monitor a low-latitude area of convection in the Pacific Ocean at 4°36′N 142°24′E / 4.6°N 142.4°E / 4.6; 142.4, located about 350 nautical miles (650 km; 400 mi) to Palau's east-southeast.

[5][6] Position fixes by 02:30 UTC on December 11 determined that its center had shifted to the north over a developing surface trough, while convective bursts occurred around the system.

[8] The Japan Meteorological Agency (JMA) (the official Regional Specialized Meteorological Center for the western Pacific Ocean[9]) first upgraded the system to a tropical depression with winds of 55 km/h (35 mph),[nb 3] at 00:00 UTC the next day, followed by the JTWC upgrading the storm's chances of developing to "high" and subsequently issuing a Tropical Cyclone Formation Alert.

[23] The JMA further upgraded the system to a typhoon by the next day, followed by the JTWC three hours later as Rai began to take a westward motion under the influence of a subtropical ridge to its north.

The same situation slightly weakened the system into a Category 4-equivalent super typhoon by 09:00 UTC, and its intensity continued to degrade, six hours later while crossing Visayas.

[33][34][35] As Rai entered Panay Gulf, its eye further weakened and its convective signature becoming disorganized as the JTWC further downgraded it to a Category 3 system six hours later.

[54] Starting on the night of December 13, land travel on bound to Visayas, Mindanao, the province of Masbate and Catanduanes were canceled according to an approved request of the Office of the Civil Defense in the country.

[55][56] Over 23,642 food packs for evacuees were also readied by the country's Department of Social Welfare and Development (DSWD), over 18,665 non-edible items as well as over ₱752,250 (US$15,040) worth of standby funds.

[58] Over 12,000 individuals in barangays across Mindanao, Visayas, and further north into Southern Luzon were also urged by the National Disaster Risk Reduction and Management Council (NDRRMC) to immediately leave their homes.

Several flights into Visayas and Mindanao from Ninoy Aquino International Airport were also delayed, rescheduled, and/or canceled, mainly from the earlier Cebu Pacific, Philippine Airlines and Airasia.

Sandbags were also placed over some houses in Tacloban City in Leyte and many individuals rushed into a grocery store in Alangalang to stock up on essential supplies.

[61] Four hours after, Rai entered the PAR, PAGASA started to hoist Tropical Cyclone Warning Signal #1 for southeastern Eastern Samar and over the Surigao provinces, including the Dinagat Islands.

[67][68] On December 15, militants of the New People's Army attacked troops evacuating residents in Surigao del Sur prior to the storm, killing three civilians.

[71] As Rai approached Vietnam after clearing the Philippines, officials held a meeting in which more than 243,254 houses across eight Vietnamese provinces were identified as "unsafe", while rice crops were harvested by farmers in preparation for the storm.

[72][73] Vietnam Airlines' flight operations were also halted due to the typhoon, while marine equipment, particularly fishing boats, were moved onto shores as a precautionary measure.

[77] In Macau, the Macao Meteorological and Geophysical Bureau (SMG) hoisted the typhoon warning signal number one in the early hours at 3AM on 20 December 2021 (MST).

[102] Strong winds and heavy rainfall also impacted Guiuan, Eastern Samar, with rough waves bashing the shores of the province, according to a news correspondent of 24 Oras.

A house was heavily destroyed by Odette's strong winds in Agusan del Norte while a barge of unknown origins was left stranded by the storm's waves on a shore, still in the province.

[nb 4] Surigao City was deprived of electricity and communications due to downed power lines while scores of trees left many roads impassable.

The mayor of Surigao City, Ernesto Matugas also estimated that 100% of the area was devastated due to Odette, also appealing for aid to the government.

[116] A terminal in Siargao Airport was also totally destroyed; the overall island was also wrecked according to the first district representative of Surigao del Norte, Francisco Jose Matugas II.

Numerous houses there were also destroyed by downed trees, with a triage of the Ignacio Locsin Arroyo Memorial District Hospital being wrecked.

[137] 78 marine vessels in Cebu also experienced sea mishaps, according to the PCG, while over 4,000 houses in Southern Leyte were destroyed due to the storm-induced storm surge.

[149] Rough storm waves damaged and destroyed 90 lobster herds on Bình Hưng Island, Cam Ranh, where losses was estimated to be more than 384 billion đồng (US$16.7 million).

[156][157] Major telecommunication networks in the country reported communication disruptions in Visayas and Mindanao but assured that their respective teams are trying to restore services.

The provinces governor, Arthur Yap, feared the situation could worsen due to a lack of a contingency fund, with supplies of necessities running dry.

[175][176] With internet service knocked out and mobile phone networks brought down in the wake of the typhoon,[177] news from the typhoon-hit areas was very limited in the critical first days after the disaster.

[178] Apple CEO Tim Cook has pledged to commit itself to rebuilding communities in both Malaysia and the Philippines while also providing short term relief and recovery efforts.