The upcoming onset of the northeast monsoon or “amihan” season may bring cooler days ahead and longer nights due to the equinoxes, the head of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said Monday.
Pagasa Administrator Nathaniel Servando said September 22 is the autumnal or fall equinox, when neither of the earth’s pole is tilted.
“It marks the beginning of the earth to tilt away from the sun, and just the beginning of longer night and shorter daytime,” he told the Philippine News Agency.
He added that meteorologically, September 22 marks the end of the northern hemisphere summer and the start of the autumn season.
Pagasa’s recorded sunrise on September 22 was 5:45 a.m. and sunset at 5:52 p.m.
Servando said sunrise yesterday was at 5:45 a.m. and sunset at 5:51 p.m., a minute earlier from the previous sunset.
Those in the equator had an equal daytime and nighttime on September 22, he said.
The Philippines, which is in the northern hemisphere, could expect the start of the winter season on December 21 (winter solstice) until March 20 (vernal or spring equinox) or the start of spring.
“The longest nighttime will be on December 21, when either of the earth’s pole reaches its maximum tilt (23.5 degrees) away from the Sun,” Servando said.
Servando said that on December 21, the day would be shorter by about one hour and 44 minutes.
For comparison, he said that last June 21, sunrise was at 5:28 a.m. and sunset was at 6:28 p.m.
On December 21, sunrise will be at 6:16 a.m. while sunset will be at 5:32 p.m.
“Then the earth’s tilt will move towards zero degree again on March 20 (during vernal or spring equinox) and daytime and nighttime will be equal again,” he said.
Meanwhile, Servando said the public could also look forward to cooler temperatures in the coming days due to the “amihan” season.
“In the coming days, the winds will be colder due to the shift from ‘habagat’ (southwest monsoon) to ‘amihan,'” he said.
However, there is no indication yet to terminate “habagat” as the prevailing weather system, Servando said.
“But normally, the onset of ‘amihan’ season falls between the last week of September to first week of October. It varies,” he said.
The onset of “amihan” season was declared on October 20, 2023 and was terminated last March 22. (PNA)