Warm ENSO anomalies with respect to neutral conditions, by season
1902-03, 1904-06, 1911-12, 1913-15, 1918-19, 1925-26, 1930-31, 1940-42, ... 1957-58, 63-64, 65-66, 68-69, 69-70, 72-73
based on Dec-Jan Nino3.4 being greater than 0.99C


Mar-May(0)


Jun-Aug(0)


Sep-Nov(0)


Dec(0)-Feb(1)


Mar-Mar(1)