The Philippine Atmospheric, Geophysical and Astronomical Services (Pagasa) advised the public in January that 2010 will be an El Niño year. The El Niño, properly the El Niño-Southern Oscillation, or ENSO, is a quasi-periodic (i.e. varies on the average from three to seven years) warming of the surface waters in the eastern Pacific Ocean coupled with the changes in surface pressure in the tropical western Pacific. This affects precipitation patterns and temperatures. The El Niño in the Philippines typically spells less typhoons, a shorter rainy season and weak monsoon activity.