Feeling the heat? Here's what heat index means
Published Mar 24, 2026 01:12 pm
Pedestrians endure the heat in downtown Davao City as the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) on Monday, March 23, declared the start of the warm and dry season. (Keith Bacongco/Manila Bulletin)
With the end of the northeast monsoon season (amihan) on March 23, the Philippines is entering its warm and dry season, when rising temperatures and humidity make the heat more intense.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) monitors how this heat is actually experienced by the body using the heat index (damang init).
“The heat actually felt by the human body (apparent temperature) cannot be accurately measured by air temperature alone. It is more accurately estimated by including data on heat and humidity (relative humidity),” PAGASA said.
The heat index combines air temperature with relative humidity to estimate the apparent temperature felt by the human body.
How heat index affects the body
PAGASA classifies the heat index into levels of risk to indicate how the body may be affected under various temperature and humidity conditions.
At the caution level (27–32°C), prolonged exposure or physical activity may cause fatigue, and heat cramps can occur.
Extreme caution (33–41°C) increases the likelihood of heat cramps and heat exhaustion, and continued activity could result in heat stroke.
The danger level (42–51°C) carries a high risk of heat cramps, heat exhaustion, and possible heat stroke.
At extreme danger (52°C and above), the risk of heat stroke is severe and requires immediate action.
PAGASA also warned that certain groups are more vulnerable to heat-related illness.
Infants and elderly individuals, people with obesity, those performing strenuous activity in hot and humid conditions, and individuals consuming excessive alcohol are particularly at risk.
Symptoms may include heavy sweating, fatigue, dizziness, rapid pulse, fainting, or loss of consciousness in severe cases.
How to stay safe in the heat
PAGASA advised the public to limit outdoor exposure during the hottest hours, drink plenty of water, wear light clothing, and use umbrellas or hats for shade.
Heavy physical activity should be done during cooler hours of the day, and tea, coffee, soft drinks, or alcohol should be avoided to prevent dehydration.
If a person shows signs of heatstroke, they should be moved to a shaded area and cooled with water or ice applied to pulse points such as the armpits, neck, wrists, ankles, or groin.
Fluids may be given if the person is conscious, but severe cases, including loss of consciousness, require immediate hospital care.
From March to June, PAGASA provides updated heat index monitoring and forecasts online at its website to help the public stay safe during the hottest months of the year.