California El Nino and La Nina Precipitation Climnatology

This is a catalog of California precipitation anomalies for previous El Niño events based upon their strength and the 10 state hydrologic regions and the 3 Sierra Nevada Precipitation Indices. It has the average for all events, weak events, moderate events, strong and very strong events and the wide range of the individual seasons that went into making up each of the averages. (For La Niña click HERE).

It cannot be stressed strongly enough that this is a climatological analysis of past events and NOT a forecasting tool. This is especially true for the averages of different strength events which are made up of what are a very broad range of conditions; some that are decidedly atypical.

The Relative Oceanic Niño Index (RONI) is used to identify El Niño (warm) and La Niña (cool) events in the tropical Pacific. The RONI is the running 3-month mean SST anomaly for the Niño 3.4 region (i.e., 5°N-5°S, 120°-170°W) minus the overall average tropical 3-month sea surface temperature anomaly (SSTA). Events are defined as 5 consecutive overlapping 3-month periods at or above the +0.5^o anomaly for warm (El Niño) events and at or below the -0.5 anomaly for cool (La Niña) events. The threshold is further 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, an event is categorized as weak, moderate, strong or very strong it must have equaled or exceeded the threshold of the highest category for at least 3 consecutive overlapping 3-month periods.

El Niño Events:
     Weak: 1951-1952, 1952-1953, 1953-1954, 1969-1970, 1977-1978, 1979-80, 1992-1993, 2004-05, 2006-07, 2014-15, 2018-19
     Moderate: 1963-1964, 1968-1969, 1976-1977, 1986-1987, 1987-1988, 1994-1995, 2002-2003, 2009-2010, 2023-2024
     Strong: 1957-1958, 1965-1966, 1972-1973
     Very Strong: 1982-1983, 1991-1992, 1997-1998, 2015-2016

ALL		Table 1. ALL El NIño - Years by Percent of Normal Categories (27 events)
% of Normal	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
<50%	1	1	0	1	1	1	0	1	1	1	0	1	2	1
50-70%	1	2	4	3	4	3	3	1	3	0	2	5	4	5
70-90%	5	5	5	5	5	7	8	5	3	5	6	2	5	3
90-110%	5	6	6	5	5	2	3	5	3	3	7	6	4	4
110-130%	10	4	5	4	3	3	1	3	4	7	4	7	3	2
130-150%	2	6	5	5	5	3	6	4	3	2	4	3	4	6
>150%	3	3	2	4	4	8	6	8	10	9	4	3	5	6
Average All	109%	109%	105%	112%	109%	120%	119%	126%	136%	137%	111%	105%	109%	117%
Max % Normal	161%	170%	165%	197%	190%	215%	201%	205%	228%	236%	177%	170%	199%	209%
Min % Normal	43%	45%	58%	48%	50%	43%	52%	38%	31%	33%	56%	38%	47%	47%

AVERAGE of ALL El Niños


WEAK		Table 2. WEAK El NIño - Years by Percent of Normal Categories (11 events)
% of Normal	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
<50%	0	0	0	0	0	1	0	1	1	1	0	0	1	1
50-70%	0	1	1	1	2	1	2	1	2	0	1	1	1	1
70-90%	2	1	2	2	2	3	3	3	1	3	1	1	2	1
90-110%	1	2	2	2	1	0	0	0	1	1	3	3	1	2
110-130%	7	3	3	3	2	1	0	0	0	0	3	4	2	0
130-150%	1	4	3	3	4	2	5	2	1	1	2	2	3	4
>150%	0	0	0	0	0	3	1	4	5	5	1	0	1	2
Average WEAK	110%	111%	108%	111%	110%	112%	114%	123%	137%	144%	112%	109%	110%	115%
Max % Normal	133%	139%	133%	141%	148%	179%	183%	205%	228%	236%	151%	135%	156%	167%
Min % Normal	81%	64%	58%	59%	59%	43%	52%	38%	31%	33%	60%	68%	48%	47%

AVERAGE of All WEAK El Niños	1951-1952	1952-1953	1953-1954	1969-1970

1977-1978	1979-1980	1992-1993	2004-2005	2006-2007

2014-2015	2018-2019


MODERATE		Table 3. MODERATE El NIño - Years by Percent of Normal Categories (9 events)
% of Normal	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
<50%	1	1	0	1	1	0	0	0	0	0	0	1	1	0
50-70%	0	1	2	2	2	2	1	0	1	0	1	3	2	2
70-90%	3	2	2	1	1	2	3	2	1	1	3	0	2	2
90-110%	2	3	3	2	3	1	2	4	2	2	3	2	1	1
110-130%	2	0	0	1	0	2	1	0	2	5	0	2	1	2
130-150%	1	1	1	1	0	0	0	1	1	0	1	0	0	0
>150%	0	1	1	1	2	2	2	2	2	1	1	1	2	2
Average MODERATE	99%	96%	97%	96%	97%	110%	110%	117%	121%	118%	100%	92%	99%	108%
Max % Normal	144%	169%	165%	159%	165%	186%	194%	162%	188%	153%	159%	162%	179%	200%
Min % Normal	43%	45%	63%	48%	50%	64%	68%	80%	67%	84%	56%	38%	47%	58%

AVERAGE of All MODERATE El Niños	1963-1964	1968-1969	1976-1977	1986-1987

1987-1988	1994-1995	2002-2003	2009-2010	2023-2024


STRONG		Table 4. STRONG El NIño - Years by Percent of Normal Categories (3 events)
% of Normal	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
<50%	0	0	0	0	0	0	0	0	0	0	0	0	0	0
50-70%	0	0	0	0	0	0	0	0	0	0	0	0	0	1
70-90%	0	1	1	1	1	1	1	0	0	0	1	1	1	0
90-110%	2	0	1	0	0	0	0	0	0	0	0	1	1	0
110-130%	0	1	1	0	1	0	0	3	2	2	1	0	0	0
130-150%	0	1	0	1	1	1	1	0	0	1	1	1	1	2
>150%	1	0	0	1	0	1	1	0	1	0	0	0	0	0
Average STRONG	112%	112%	102%	126%	111%	133%	124%	123%	142%	131%	115%	103%	104%	118%
Max % Normal	151%	146%	128%	159%	139%	169%	154%	130%	168%	141%	146%	137%	131%	147%
Min % Normal	91%	77%	79%	77%	77%	82%	78%	112%	127%	123%	86%	73%	80%	68%

AVERAGE of All STRONG El Niños	1957-1957	1965-1966	1972-1973


VERY STRONG		Table 5. VERY STRONG El NIño - Years by Percent of Normal Categories (4 events)
% of Normal	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
<50%	0	0	0	0	0	0	0	0	0	0	0	0	0	0
50-70%	1	0	1	0	0	0	0	0	0	0	0	1	1	1
70-90%	0	1	0	1	1	1	1	0	1	1	1	0	0	0
90-110%	0	1	0	1	1	1	1	1	0	0	1	0	1	1
110-130%	1	0	1	0	0	0	0	0	0	0	0	1	0	0
130-150%	0	0	1	0	0	0	0	1	1	0	0	0	0	0
>150%	2	2	1	2	2	2	2	2	2	3	2	2	2	2
Average VERY STRONG	124%	130%	119%	141%	133%	153%	146%	161%	159%	165%	133%	127%	133%	142%
Max % Normal	161%	170%	161%	197%	190%	215%	201%	204%	213%	208%	177%	170%	199%	209%
Min % Normal	70%	74%	63%	85%	74%	87%	83%	103%	78%	82%	83%	69%	68%	69%

AVERAGE of All VERY STRONG El Niños	1982-1983	1991-1992	1997-1998	2015-2016

		Table 6. Sorted Catalog of El Niño Years (1950-1951 to 2024-2025)
WEAK	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
1951-1952	122%	132%	133%	137%	136%	144%	147%	149%	174%	167%	133%	134%	130%	159%
1952-1953	119%	106%	99%	97%	86%	80%	90%	72%	75%	82%	98%	103%	79%	95%
1953-1954	111%	94%	81%	78%	86%	81%	89%	80%	97%	80%	93%	93%	85%	93%
1969-1970	115%	115%	113%	105%	101%	78%	83%	61%	64%	81%	100%	114%	102%	85%
1977-1978	133%	139%	122%	141%	148%	179%	183%	205%	228%	221%	151%	135%	156%	167%
1979-1980	111%	120%	132%	127%	128%	130%	137%	163%	192%	213%	127%	114%	142%	147%
1992-1993	123%	131%	125%	130%	139%	153%	147%	172%	222%	236%	139%	124%	141%	142%
2004-2005	102%	113%	110%	129%	138%	159%	143%	202%	226%	235%	130%	109%	136%	137%
2006-2007	81%	64%	58%	59%	59%	43%	52%	38%	31%	33%	60%	68%	62%	60%
2014-2015	85%	78%	86%	84%	60%	62%	55%	70%	62%	95%	73%	73%	48%	47%
2018-2019	113%	130%	132%	135%	128%	128%	132%	139%	139%	140%	124%	130%	126%	133%

MODERATE	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
1963-1964	83%	70%	82%	65%	73%	65%	78%	80%	82%	100%	75%	68%	75%	76%
1968-1969	125%	133%	145%	133%	161%	178%	194%	162%	188%	116%	143%	129%	172%	200%
1976-1977	43%	45%	70%	48%	50%	70%	68%	110%	91%	125%	56%	38%	47%	58%
1986-1987	81%	67%	68%	61%	61%	64%	72%	87%	67%	97%	71%	63%	59%	66%
1987-1988	81%	76%	63%	70%	66%	79%	85%	108%	102%	129%	79%	66%	66%	79%
1994-1995	144%	169%	165%	159%	165%	186%	174%	157%	188%	153%	159%	162%	179%	164%
2002-2003	116%	109%	92%	108%	93%	102%	102%	99%	113%	84%	105%	110%	96%	112%
2009-2010	106%	99%	92%	113%	109%	118%	116%	107%	118%	129%	105%	101%	113%	121%
2023-2024	110%	97%	94%	104%	95%	125%	105%	140%	143%	127%	107%	94%	87%	91%

STRONG	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
1957-1958	151%	146%	128%	159%	139%	169%	154%	130%	168%	141%	146%	137%	131%	147%
1965-1966	91%	77%	79%	77%	77%	82%	78%	112%	127%	128%	86%	73%	80%	68%
1972-1973	94%	112%	99%	143%	118%	147%	139%	127%	130%	123%	112%	98%	101%	138%

VERY STRONG	N Coast	Sacramento	N Lahontan	SF Bay	S Joaquin	C Coast	Tulare Lk	S Lahontan	S Coast	Colo River	Calif	8SI	5SI	6SI
1982-1983	161%	170%	161%	197%	190%	208%	201%	204%	211%	208%	177%	170%	199%	209%
1991-1992	70%	74%	63%	85%	74%	103%	83%	142%	133%	182%	83%	69%	68%	69%
1997-1998	151%	165%	130%	182%	160%	215%	193%	194%	213%	187%	167%	157%	162%	192%
2015-2016	116%	109%	123%	100%	108%	87%	106%	103%	78%	82%	105%	112%	105%	96%