‘SIZZLING CITY’: Iloilo City heat index hits 47°C as urbanization bites

By Rjay Zuriaga Castor

Concrete pavements, fewer trees, and shrinking open spaces are making Iloilo City significantly hotter than nearby towns, with the heat index already reaching a dangerous 47 degrees Celsius, city officials said.

Patricia Anne Constantinopla, resident meteorologist of the city’s Emergency Operations Center, said rapid urbanization has worsened the Urban Heat Island (UHI) effect and intensified extreme heat conditions.

Constantinopla said the city recorded its highest heat index — the temperature felt by the human body — on May 7 at 47 degrees Celsius, which falls under the “danger” category set by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

Under PAGASA’s classification, a heat index of 42 to 51 degrees Celsius poses a danger of heat cramps and heat exhaustion, with heat stroke probable for those exposed for prolonged periods.

She said March, April, and May are typically the peak months for high heat indices, with temperatures usually climbing by May.

Localized data gathered by the city’s Emergency Operations Center, however, showed that this year’s heat levels are significantly higher than those recorded in 2025.

“Last year, we averaged around 43 degrees Celsius in April and early May. But now, based on our data this April, the average has already reached 44 degrees Celsius, and we already peaked at 47 degrees Celsius at the start of May,” Constantinopla said during a press conference Thursday, May 14.

“Usually, on a day-to-day basis, for four consecutive days, the heat index ranges from 44 to 46 degrees Celsius based on our localized data,” she added.

She stressed that rising temperatures are directly linked to urbanization.

“That is the effect of urbanization. The urbanization enhances the extreme heat because it increases the UHI effect,” Constantinopla said.

The UHI effect refers to the phenomenon in which urban areas become significantly warmer than surrounding rural or natural areas due to human-made surfaces, reduced vegetation, and heat generated by human activities.

Iloilo City, one of the fastest-growing urban centers in Western Visayas, has seen a building boom over the past decade, with commercial developments, road widening projects, and high-rise residential towers reshaping much of its central districts.

Neil Ravena, executive director of the Crisis Management Council, also acknowledged that the extreme heat in the city has been aggravated by rapid urban development.

“Because of the concrete pavements, we now have fewer open grounds and green spaces. Heat reflected by concrete surfaces stays longer because there are fewer plants and trees to absorb it,” Ravena said.

Ravena clarified that the city’s cooling stations are only a temporary response to the extreme heat.

He said they are not a substitute for long-term environmental measures such as tree-planting and greening programs.

“The reason why we resorted to cooling stations is not to replace tree-planting and greening activities. Nothing can replace those interventions. Cooling stations are simply a response to the current situation, especially with the severe peak in the heat index,” he said.

He added that the benefits of the city’s ongoing tree-planting initiatives may only be felt within the next five years.

Ravena said the city government is preparing around 100,000 seedlings for planting by July or August, depending on weather conditions.

He also said the city created a team tasked with identifying and assessing available open spaces that can still be converted into planting areas.

The city government is also planning to enter into memorandum agreements with homeowners’ associations in subdivisions to encourage them to designate open spaces within their communities as tree-planting sites.