The La Niña following the unusually strong 1997/98 El Niño lasted 33 months and spanned three winters.
Notes on verification
Multiple reputable sources (WMO, NASA, NC State) confirm the 1998-2001 'triple-dip' La Niña spanning three winters, but the exact figure of 33 months was not independently verified in precise wording, though it is consistent with the confirmed timeframe.
Sources
- Say Goodbye to a Historic El Niño and Hello to La Niña (smithsonianmag.com)
- https://public.wmo.int/topics/el-nino-la-nina (public.wmo.int)
- https://climate.ncsu.edu/blog/2022/11/winter-outlook-for-2022-23-la-nina-lives-on/ (climate.ncsu.edu)
- https://science.nasa.gov/earth/earth-observatory/la-nina-times-three-150691/ (science.nasa.gov)