El Niño translates to "the boy" in Spanish. The term is thought to have originated in the 1600s when fishermen first started to notice unusually warm water in the Pacific Ocean. It originated as "El Niño de Navidad" because it typically peaks around December, according to NOAA (Navidad is Spanish for "Christmas."). La Niña means little girl in Spanish, it has the opposite effect of El Niño and is sometimes referred to as El Viejo, anti- El Niño or "a cold event."