MANILA—State weather bureau PAGASA on Friday said the heat index or human-perceived temperature in Metro Manila could reach to 38.2 degrees Celsius.

Heat index at the PAGASA Science Garden station in Quezon City is forecast between 34.3 to 38.2 degrees Celsius, weather specialist Raymond Ordinario told Teleradyo.

A high heat index could also be felt in the Dagupan station (39 degrees), Laoag (39.1 degrees) and Sangley (39.6 degrees).

PAGASA classifies heat index as human discomfort index that gives the "apparent" temperature, or what humans perceive or feel as the temperature affecting their body. High air temperatures and high relative humidity will give high apparent temperatures or indices.

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The agency advised the public to stay indoors as much as possible, wear light-colored clothing and stay hydrated.

A heat index ranging from 32 to 41 degrees Celsius falls under “extreme caution” due to possible heat cramps and heat exhaustion while continuing activity could result in heatstroke.

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So far, the highest heat index this year was recorded in Dagupan, Pangasinan at 49 degrees Celsius on April 6.