For about the last two years we have seen almost continuous La Niña conditions where ocean temperatures in the eastern equatorial Pacific are 0.5º or more below the long-term average. Despite this we have continued to see very warm global temperatures. An index that tracks the occurrence of La Niñas is the Southern Oscillation Index (SOI). The SOI is calculated based upon pressure differences between Tahiti and Darwin , Australia. Positive anomalies, seen in blue on the chart below correlate well with La Niña conditions. The warmest year on record, which occurred during a strong El Niño was 2016. We expect temperatures warmer than normal during an El Niño, but not during a La Niña. We would normally see some global cooling during a La Niña, but 2021 was still the seventh warmest year on record.
The chart below (from climate.gov) shows the average impacts of a La Niña. In some places, conditions correlated well. For example, the Pacific Northwest, winter and spring conditions were cooler and wetter than normal. For Seattle, temperatures from December 2021 through May 2022 were nearly 3ºF below normal. The nearly 36 inches of rain exceeded the normal by over five inches.
Looking at the weather from Los Angeles International Airport, we can see that December 2021, did not correlate to the warmer and drier conditions expected during a La Niña for southern California. Temperature was 3.3ºF below normal while the 8.24 inches of rain exceeded the normal by six inches. Starting in January, however, we saw the warmer dry conditions normally expected for Southern California during a La Niña. Temperatures averaged 1.4º F above normal and rainfall totaled 1.46 inches, well below the normal of 8.46 inches.
Unusual for a La Niña year, unprecidented heatwaves occurred in North America, China, the European continent and the UK where their hottest day on record with a temperature of 104º F was recorded. See https://earthobservatory.nasa.gov/images/150152/a-july-of-extremes for more detail.