The terms “El Nino” and “La Nina” are actually a part of a three stage climate phenomenon. The third stage is a “neutral” stage in which neither El Nino or La Nina are occuring. All three of these terms are encompassed in the term ENSO, or El Niño–Southern Oscillation. This is when the Pacific ocean will either have warmer waters as Christmas approaches, El Nino, or it will have a neutral water temperature, or colder temperature, La Nina. The area most affected by the warming or cooling of the waters is the tropical zone of the Pacific Ocean, most specifically, just south of the equator.
What does this mean for us in the US? Well, what happens when there is an El Nino year is that the winds often will become westerly (originating from the west) or very weak easterly winds. This will often push stronger storms to the west coast of the US that will bring higher amounts of snowfall and rain to California, Oregon, Washington, Utah, Idaho, Montana, Arizona, Colorado, and Wyoming. When there is a La Nina year, this is often the opposite. The winds become stronger easterly winds and a majority of the stronger storm systems impact the North East of the US.
Link to article:EE ElNino Judge Memorial Catholic High School