what is a el nino winter

El Niño is a natural climate phenomenon marked by warmer-than-average sea surface temperatures in the central and eastern Pacific Ocean near the equator, which occurs on average every 2-7 years. El Niños influence on the U.S. is weak during the summer and more pronounced starting in the late fall through spring. By winter, there is an 84% chance of greater than a moderate strength El Niño, and a 56% chance of a strong El Niño developing. During strong El Niño winters, we typically see heavy rainfall in the southwestern United States and in Southern California. Historically, we see more snowfall in the Sierra and southern Rockies, but less snow in the Northeast. However, El Niño is not a guarantee, and it only tilts the odds in favor of certain climate outcomes. El Niño can cause a range of impacts, such as increasing the risk of heavy rainfall and droughts in certain locations around the world.