Warm and humid weather is expected to affect voters on Monday due to the prevailing Easterlies, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said.

PAGASA Weather Specialist Rhea Torres said in a phone interview that air temperatures in Metro Manila could range from 25°C to 34°C. However, the heat index—or the temperature felt by the human body—may soar to 42°C.

“Despite the heat, we are also expecting the occurrences of thunderstorms. In the event that it is really hot during noon time, there’s a chance that the thunderstorms in the afternoon and night time could be stronger,” Torres said.

For Monday, Torres noted that generally rainy weather is expected in Extreme Northern Luzon, particularly in Batanes and the Babuyan Islands, due to a frontal system. In contrast, the rest of the country, including Metro Manila, will experience hot and humid conditions, with possible thunderstorms in the evening.

PAGASA issues thunderstorm advisories through its official Facebook page at least three hours before expected occurrences.

With millions of Filipinos expected to visit public schools to vote, PAGASA advises the public to plan their voting hours to minimize exposure to extreme heat.

“The time that the voters should avoid is between 10 a.m. to 11 a.m. until 3 p.m., because it is considered as the peak hours of the day. They should also avoid enclosed spaces, and long queues because it will make them susceptible for heat stroke and other heat-related illnesses,” Torres warned.

She strongly encouraged voters to cast their ballots either at the opening of polling precincts at 7 a.m. or in the late afternoon.

“As much as possible, we are also suggesting the voters to wear light clothes in case of intense sweating, and to drink lots of water to avoid dehydration,” she added.