California could be headed for a wetter and potentially more damaging than normal winter this year. The latest El Niño advisory from NOAA says there is a greater than 90% chance the developing El Niño becomes very strong this fall and winter—and a 69% chance it reaches historic ocean-temperature strength between October and December, but NOAA is not predicting “69% more rain.”
That 69% figure describes the probability of an exceptionally powerful El Niño. It is not a rainfall forecast. NOAA separately gives much of coastal California greater than even odds of receiving above-normal precipitation between December and April, with the strongest wet signal currently concentrated from January through March.
A strong El Niño commonly directs more Pacific storms toward California, particularly Southern California. That could improve water supplies and produce substantial Sierra snowfall, but warmer storms could also bring more rain than snow at lower elevations. Repeated storms would increase the danger of flooding, coastal erosion and debris flows below wildfire burn scars.
The important qualification is that El Niño changes the odds—it does not guarantee a particular result. NOAA says the California wet signal is strong, but it cannot yet predict how many storms will arrive or how much rain will fall. The accurate takeaway is: California has an elevated chance of a wetter-than-normal winter, not a forecast for 69% more rain.
AI contributed to this story.
