While the Philippines is still in the northeast monsoon (amihan) season, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) began releasing daily heat index reports on March 1 to help the public prepare for the warmer and drier months ahead.
In an interview with the Manila Bulletin, PAGASA Weather Specialist Ana Clauren-Jorda explained that daily monitoring began as the amihan season is nearing its end, which may occur in mid-March, marking the transition to the dry and warm season that will last until May.
Heat index explained
She said the heat index offers a more accurate measure of how hot it feels by factoring in air temperature and humidity, especially during the dry season.
As high humidity reduces the body’s ability to cool itself through sweat, it makes the heat feel more intense.
Clauren-Jorda further pointed out that PAGASA releases heat index reports to guide those at higher risk of heat-related illnesses, such as heatstroke and heat stress.
“We provide heat index reports so that people who are vulnerable to the heat—such as children, the elderly, or outdoor workers—are better prepared for the heat,” she said in Filipino.
She added that understanding the heat index is important in preventing heat-related issues, particularly in cities like Metro Manila, where the urban heat island effect makes temperatures feel even higher.
It is also relevant in schools without air conditioning or those vulnerable to extreme heat.
“In areas without air conditioning or in more urbanized areas, the heat index becomes even more relevant because the heat can be more oppressive,” she said.
PAGASA’s heat index monitoring also helps local government units and schools decide if class suspensions are necessary during extreme heat.
PAGASA releases heat index updates daily at 5 p.m.
“By releasing daily updates, we ensure that people are aware of the heat conditions throughout the dry season. This helps individuals plan their activities, know when to stay indoors, and take the proper precautions when the heat becomes extreme,” Clauren-Jorda said.
Heat index classifications
When the heat index reaches 27 to 32 degrees Celsius (°C), it signals “caution,” as fatigue may occur with prolonged exposure or activity, and heat cramps are possible.
Meanwhile, a heat index between 33 to 41°C indicates “extreme caution,” with heat cramps and heat exhaustion being possible, and continuing activity could lead to heatstroke.
A heat index between 42 to 51°C is categorized as “danger,” as heat cramps and heat exhaustion are likely, and heatstroke is probable with continued exposure.
Finally, a heat index of 52°C and beyond signals “extreme danger,” with heatstroke being imminent.
To prevent heat-related issues, it is advised to limit outdoor exposure, drink plenty of water, and avoid beverages like tea, coffee, soda, and alcohol.
Wearing hats, umbrellas, and long-sleeved clothing outdoors is recommended, and strenuous activities should be scheduled for cooler parts of the day.