I searched about "urban heat island" and it was defined as an "urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities".  Way back in 2012, a weather specialist, Nivagine Nievares, announced that findings in her Masteral Thesis showed that indeed there is a 1°C to 2°C  difference between temperature in Manila and in surrounding towns. In fact, she said in the newspaper interview that Metro Manila can be considered a heat urban island.

Well, I know what that feels like because I grew up in a rural area, which is one of the cooler places in the Philippines.  Whenever I go to Manila, the Philippine capital city, I feel very warm. It is so warm that when I started University in Manila, I had the option of dormitory on campus with no aircon or off-campus dormitory about 15 minutes walk, but it had an airconditioner. So you can guess what I chose.

I think, one of the things that makes urban areas warmer are all rapid developments and construction like high-rise buildings and paved roads.  All these metal, cement and asphalt absorbs and traps heat from the sun unlike ground cover like grass and other plants.

To lessen temperature, it is good idea to have plants on rooftops specially in urban areas.  In France, they recently (sometime in March) approved a law that would require new buildings to have either plants or solar panels covering part of their rooftops. These are called green roofs and they have an insulating effect on the buildings. They not only add to the cooling effect in the urban areas but plants in particular create additional places for birds and other animals to build their nests/homes.

Another reason for high temperatures is pollution in the air, which blocks hot air from rising to the atmosphere.  This pollution can be attributed to industries and vehicles on the roads. When we come from the province and enter the highway leading into Manila, we can see the pollution and the dark grey sky above the city.  There is no doubt that this is air pollution over Metro Manila.

It is sad, but yes, Metro Manila, Philippines is now an "urban heat island".