GENERAL SANTOS CITY, Philippines — October 20, 2026 — The Intertropical Convergence Zone (ITCZ) is expected to bring cloudy skies, scattered rains and thunderstorms to the Zamboanga Peninsula on Tuesday, while the rest of Mindanao will experience partly cloudy to cloudy conditions with isolated rain showers or localized thunderstorms, according to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).
In its 5 a.m. regional weather forecast issued on October 20, PAGASA’s Mindanao station (MINPRSD) warned that moderate to occasionally heavy rainfall over the Zamboanga Peninsula could trigger flash floods and landslides. Similar hazards are possible elsewhere in Mindanao during severe thunderstorms.
The forecast is valid from 5 a.m. on October 20 until 5 a.m. on October 21, covering the island’s major regions, including the Zamboanga Peninsula, Northern Mindanao, Davao Region, SOCCSKSARGEN, Caraga and the Bangsamoro Autonomous Region in Muslim Mindanao (BARMM).
Zamboanga Peninsula faces persistent rain and thunderstorm activity
Zamboanga City, Zamboanga del Norte, Zamboanga del Sur, Zamboanga Sibugay and Isabela City are expected to experience cloudy skies with rain showers and thunderstorms throughout the forecast period.
Temperatures in the peninsula’s localities are expected to range from the mid-20s to the low 30s Celsius, with daytime highs reaching 34°C in Zamboanga City, Zamboanga del Norte and Isabela City.
Zamboanga Sibugay is forecast to record temperatures of 24°C to 32°C, while Zamboanga del Sur may experience temperatures ranging from 26°C to 34°C.
PAGASA’s warning highlights the potential for flash floods and landslides, particularly in areas where rainfall becomes moderate to heavy. Communities near rivers and creeks, in low-lying areas, and along or below steep slopes should remain alert to rapidly changing conditions.
The ITCZ is a zone where winds converge, encouraging the development of clouds and rain-producing weather systems. Its influence can sustain periods of rainfall and thunderstorms, although the timing and intensity of individual rain events may vary by locality.
Northern Mindanao may experience localized thunderstorms
Across Northern Mindanao, including Bukidnon, Camiguin, Lanao del Norte, Misamis Occidental and Misamis Oriental, partly cloudy to occasionally cloudy skies are expected, with isolated rain showers or thunderstorms.
Bukidnon is forecast to experience temperatures of 19°C to 30°C during the period, making it one of the cooler areas in the regional forecast. Camiguin may record temperatures of 24°C to 32°C, while Lanao del Norte, Misamis Occidental and Misamis Oriental are expected to reach daytime highs of around 32°C.
Although rainfall is expected to be more localized outside the Zamboanga Peninsula, PAGASA cautioned that severe thunderstorms could still trigger flash floods and landslides.
Localized thunderstorms can develop over specific communities even when surrounding areas remain relatively dry. Residents should therefore avoid assuming that conditions are safe simply because rainfall is absent in their immediate vicinity.
Davao Region faces isolated rain showers and thunderstorms
Metro Davao, Davao del Norte, Davao del Sur, Davao Oriental, Davao de Oro and Davao Occidental are forecast to experience partly cloudy to at times cloudy skies, with isolated rain showers or thunderstorms.
Temperatures are expected to reach 35°C in Metro Davao and Davao del Norte, 36°C in Davao del Sur and Davao Oriental, 33°C in Davao de Oro, and 32°C in Davao Occidental.
Davao del Sur and Davao Oriental are among the warmer areas in the forecast, with minimum temperatures around 24°C to 26°C.
Despite the generally partly cloudy outlook, residents should remain cautious during thunderstorms, particularly in areas vulnerable to sudden flooding, slope instability and strong weather conditions associated with severe storm activity.
Motorists should exercise caution on roads affected by heavy rain, reduced visibility or water accumulation, while residents in flood-prone communities should monitor local government advisories and be prepared to move to safer locations if conditions deteriorate.
SOCCSKSARGEN, Caraga also under thunderstorm watch
The provinces of North Cotabato, South Cotabato, Sultan Kudarat and Sarangani are expected to experience partly cloudy to occasionally cloudy skies, with isolated rain showers or thunderstorms.
Forecast temperatures range from 22°C to 34°C across SOCCSKSARGEN, with Sultan Kudarat potentially reaching the highest daytime temperature in the group at 34°C.
In Caraga, Agusan del Norte, Agusan del Sur, Surigao del Norte, Surigao del Sur and the Dinagat Islands are also expected to experience similar weather conditions.
Daytime temperatures in the Caraga provinces could reach 34°C, while minimum temperatures are expected to range from 25°C to 26°C in most areas.
PAGASA’s regional outlook indicates that rainfall outside the Zamboanga Peninsula is expected to be isolated rather than widespread. However, the possibility of severe thunderstorms means that short periods of intense rainfall could still create dangerous conditions in susceptible locations.
Residents in communities with a history of flooding or landslides should remain vigilant, particularly during periods of heavy downpour.
BARMM provinces to experience varying weather conditions
Across BARMM, Cotabato City, Basilan, Lanao del Sur, Tawi-Tawi, Maguindanao del Norte and Maguindanao del Sur are forecast to experience partly cloudy to occasionally cloudy skies with isolated rain showers or thunderstorms.
Sulu is expected to have cloudier conditions, with rain showers and thunderstorms throughout the forecast period.
Temperatures in the region are expected to vary considerably. Lanao del Sur may record temperatures as low as 21°C, with highs of 28°C, while Cotabato City could reach 33°C. Basilan may experience temperatures between 24°C and 34°C, and both Maguindanao del Norte and Maguindanao del Sur could reach daytime highs of 33°C.
Tawi-Tawi is forecast to experience temperatures of 26°C to 31°C, while Sulu may record temperatures ranging from 25°C to 30°C.
The possibility of thunderstorms across the region calls for continued caution, particularly in low-lying communities, areas near waterways and locations vulnerable to slope failures.
Northwest to west winds; seas may reach 2.5 meters
PAGASA said light to moderate winds from the northwest to west are expected across much of Mindanao, accompanied by slight to moderate sea conditions.
Wave heights across the broader forecast area may range from 0.6 meter to 2.5 meters, depending on location and prevailing conditions.
While some coastal areas are forecast to experience slight seas, others may encounter moderate conditions. The range indicates that sea conditions will not be uniform across Mindanao’s extensive coastline.
Fisherfolk, boat operators and other people engaged in coastal activities should check local marine advisories and assess actual sea conditions before departing. Small boats and other vessels operating in exposed waters should exercise appropriate caution, especially when thunderstorms develop.
The forecast also identifies variable winds in parts of Caraga, including Surigao del Sur and the Dinagat Islands, while Basilan is expected to experience light to moderate northwesterly winds.
PAGASA urges vigilance amid flood and landslide risks
The principal concern in Tuesday’s outlook is the potential for heavy rainfall in the Zamboanga Peninsula and severe thunderstorm activity elsewhere in Mindanao.
Flash floods can develop rapidly, particularly in urban drainage systems, low-lying communities and areas near rivers and streams. Landslides may occur on steep or unstable slopes, especially where the ground becomes saturated by prolonged or intense rainfall.
Residents should avoid crossing flooded roads and waterways, watch for rising water levels, and heed evacuation instructions from local disaster risk reduction and management offices. Communities near steep slopes should also watch for warning signs such as new ground cracks, leaning trees or posts, and unusual sounds or movement from hillsides.
People planning travel should account for the possibility of rain-related delays and reduced road visibility. Those working outdoors or conducting fishing and maritime activities should monitor weather developments throughout the day.
PAGASA emphasized that the forecast covers expected regional weather conditions and that actual conditions may vary by locality. Residents are encouraged to follow subsequent bulletins and official advisories for updates.
For additional information, PAGASA’s Mindanao station listed telephone numbers 8922-1992 and 8927-1335 and its official website, bagong.pagasa.dost.gov.ph.
Source: Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), Mindanao Regional Weather Forecast, issued at 5 a.m. on October 20, 2026, valid until 5 a.m. on October 21, 2026.