The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) announced that the summer solstice, the longest day of the year, will happen on Friday, June 21.

In a statement on Thursday, PAGASA said the Philippines would experience 13 hours of daytime.

"During the Summer Solstice, the Sun is at its highest or most northerly point in the sky. The Tropic of Cancer, situated 23.5 degrees north of the equator, is illuminated directly by the Sun during this time," PAGASA said.

Astronomers said this is an indication of summer in the northern hemisphere and winter in the southern hemisphere.