This is a catalog of nationwide "winter" precipitation anomalies for previous La Niña events.  This is a climatological analysis and not a forecasting tool.  Please note that even within a single category the broad range of conditions; some that are decidedly "atypical".

The Oceanic Niño Index (ONI) is used to identify La Niña (warm) and La Niña (cool) events in the tropical Pacific. The ONI is the running 3-month mean SST anomaly for the Niño 3.4 region (i.e., 5°N-5°S, 120°-170°W). Events are defined as 5 consecutive months at or above the -0.5° anomaly for warm (El Niño) events and at or bLaow the -0.5° anomaly for cool (La Niña) events.

El Niño thresholds are broken down into Weak (with a 0.5° to 0.9° SST anomaly), Moderate (1.0° to 1.4°), Strong  (1.5° to 1.9°), and Very Strong (≥ 2.0°) events. For the purpose of this report for an event to be weak, moderate, strong or very strong it must have equaled or exceeded the higher threshold for at least 3 months. Weak: 2004-05, 2006-07, 2014-15, 2018-19 Moderate: 1986-87,1994-95, 2002-03, 2009-10 Strong: 1987-88, 1991-92, 2023-24 Very Strong: 1982-83, 1997-98, 2015-16

La NIña thresholds are broken down into Weak (with a -0.5° to -0.9° SST anomaly), Moderate (-1.0° to -1.4°), Strong  (-1.5° to -1.9°) events. For the purpose of this report for an event to be weak, moderate, strong or very strong it much have equaled or exceeded the higher threshold for at least 3 months. Weak: 1983-84, 1984-85, 2000-01, 2005-06, 2008-09, 2016-17, 2017-18, 2022-23 Moderate: 1995-96, 2011-12, 2020-21, 2021-22 Strong: 1988-89, 1998-99, 1999-00, 2007-08, 2010-11

* December through February.

 La Niña Temperature Anomalies:
Winter (December, January, February) 

Weak La Niña (ONI = -0.5 to -0.9 °C)

1983-84  1984-85  2000-01 2005-06 2008-09 2016-17 2017-18 2022-23

Moderate La Niña (ONI = -1.0 to - 1.4 °C)

1995-96   2011-12 2020-21 2021-22

Strong La Niña (ONI = -1.5 to - 1.9 °C)

1988-89 1998-99 1999-00  2007-08 2010-11