jetstream_Nina_binned_1240.png

The jet stream pattern during La Niña winters, shown as the average zonal (west-east) wind at 300 millibars (i.e., the altitude at which the air pressure is 300 millibars) for all La Nina winters 1950–2023. Shading and arrows both indicate the wind speed. Positive values indicate westerlies, and negtive values indicate easterlies. The core of the jet stream does not extend as far to the east over the Pacific compared to El Niño winters. NOAA climate.gov image from NCEP/NCAR Reanalysis data and analysis by Michelle L'Heureux.