El Niño / La Niña
Anomolies Anuales
      Sea surface temperature anomalies in the Niño 3.4 region (5ºN-5ºS, 120º-170ºW) of the eastern and central equatorial Pacific Ocean based on the 1971-2000 base period were obtained from the Climate Prediction Center back through 1950. They were then averaged over the five month period from December to April each year. Local analysis of the anomalies led to breaking the data into the five groups listed below.
      Strong El Niño  (Average anomaly greater than +0.65 degrees C)
      Weak El Niño  (Average anomaly between +0.30 and +0.65 degrees C)
      Neutral  (Average anomaly between -0.29 and +0.29 degrees C)
      Weak La Niña  (Average anomaly between -0.30 and -0.65 degrees C)
      Strong La Niña  (Average anomaly less than -0.65 degrees C)

      Using these breakups for the December through April time period, the years since December 1950 that fall into each category are listed below (the average anomaly based on 1971-2000 normals is in parentheses):
Strong El Niño
1983 (+2.23)
1998 (+1.99)
1992 (+1.78)
1958 (+1.36)
1987 (+1.28)
1973 (+1.14)
1966 (+1.14)
2003 (+0.89)
1969 (+0.89)
1995 (+0.79)
 
 
 
 
Weak El Niño
1970 (+0.63)
2005 (+0.50)
1988 (+0.46)
1977 (+0.44)
1993 (+0.43)
1959 (+0.42)
1980 (+0.39)
1964 (+0.33)
1952 (+0.32)
1991 (+0.31)
1978 (+0.30)
 
 
 
Neutral
1953 (+0.28)
2004 (+0.19)
1990 (+0.17)
1982 (+0.14)
1979 (+0.14)
1954 (+0.14)
1994 (+0.12)
2002 (+0.07)
1957 (+0.05)
1960 (-0.06)
1961 (-0.11)
1997 (-0.22)
1981 (-0.23)
1972 (-0.28)
Weak La Niña
1968 (-0.59)
2006 (-0.55)
2001 (-0.54)
1951 (-0.54)
1984 (-0.53)
1986 (-0.52)
1975 (-0.51)
1967 (-0.46)
1965 (-0.40)
1963 (-0.33)
1962 (-0.31)
 
 
 
Strong La Niña
1989 (-1.54)
1974 (-1.44)
1971 (-1.37)
2000 (-1.33)
1999 (-1.26)
1976 (-1.19)
1985 (-1.08)
1956 (-0.94)
1955 (-0.85)
1996 (-0.67)
 
 
 
 
Note: 1951 represents December 1950 through April 1951, etc.
      The data shows that since 1950 the winter/early spring with the strongest El Niño was 1983, while the strongest La Niña was 1989.