Porto Santo Island: The weather bureau announced Tuesday the beginning of northeast monsoon (amihan) season, which will bring cold air in most parts of the country. "Over the past several days, the high pressure area over Siberia has strengthened, leading to a strong surge of northeasterly winds which is expected to affect the northern portion of Luzon beginning today and tomorrow, after the passage of Super Typhoon Pepito,' the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said. According to Philippines News Agency, PAGASA added that the successive surges of northeasterly winds are expected over the next two weeks, leading to an increase in atmospheric pressure and cooling of surface air temperature over the northern portion of Luzon. "The development of these meteorological patterns indicate the onset of the amihan season,' it said. Meanwhile, amihan season will cause the increasing prevalence of rough sea conditions, especially over the seaboards of Luzon in the co ming months, according to PAGASA. The onset of amihan season usually falls between the last week of September to first week of October. Last year, the onset of amihan season was declared on Oct. 20, and was terminated on March 22, 2024.