When does El Niño rain actually arrive in San Diego?
Mostly January through March. In the two biggest El Niño winters, 1982–83 and 1997–98, February and March alone brought about 57% of the year's rain at San Diego's airport.
- Feb + Mar share, 1997–98
- 57%
- Feb + Mar share, 1982–83
- 57%
- Oct 1–28, 2026
- 1.54 in
- Normal water year
- 9.79 in
9.86" of 17.16" at San Diego Intl
10.45" of 18.49"
Normal for all of October is 0.50" (1991–2020)
1991–2020 normal, San Diego Intl
The short version
- February and March brought 10.45" of 1982–83's 18.49" and 9.86" of 1997–98's 17.16" at San Diego's airport.
- October was almost dry in every analog year: 0.05" in 1982, 0.02" in 1997, 0.43" in 2015 and 0.01" in 2023.
- October 2026 already has 1.54" through the 28th, and 1.04" of that came from Tropical Storm Rachel on Oct 10–12.
- Daniel Swain of Weather West expects peak California impacts from December through March, with January and February most likely to be extreme.
- 2015–16 was a strong El Niño and still gave the airport only 8.18", with 0.05" in February.
El Niño rain in San Diego is a late-winter thing. At San Diego International Airport, the two biggest El Niño winters on record there, 1982–83 and 1997–98, each got more than half their rain in February and March. October and November mattered very little. That's worth knowing this fall, because October 2026 has already been unusually wet.
10.45"
Feb + Mar 1983
of 18.49" for the year
9.86"
Feb + Mar 1998
of 17.16" for the year
1.54"
Oct 1–28, 2026
1.04" from Rachel
0.05"
Feb 2016
in a strong El Niño year
Month by month in the big El Niño years
Rain by month in San Diego's two wettest El Niño winters
San Diego International Airport, October to May
NOAA Regional Climate Centers ACIS, San Diego Intl Airport (KSAN), retrieved Oct 29, 2026. March 1983 (6.57") and February 1998 (7.65") carried those winters.
| Month | 1982–83 | 1997–98 | 2015–16 | 2023–24 | Normal |
|---|---|---|---|---|---|
| Oct | 0.05 | 0.02 | 0.43 | 0.01 | 0.50 |
| Nov | 2.10 | 1.17 | 1.54 | 0.61 | 0.79 |
| Dec | 1.43 | 1.35 | 0.88 | 0.79 | 1.67 |
| Jan | 2.10 | 2.68 | 3.21 | 3.65 | 1.98 |
| Feb | 3.88 | 7.65 | 0.05 | 4.58 | 2.20 |
| Mar | 6.57 | 2.21 | 0.76 | 2.54 | 1.46 |
| Apr | 1.74 | 1.11 | 0.55 | 0.16 | 0.65 |
| May | 0.01 | 0.64 | 0.44 | 0.07 | 0.28 |
| Water-year total (Oct–Sep) | 18.49 | 17.16 | 8.18 | 12.43 | 9.79 |
Oct
- 1982–83
- 0.05
- 1997–98
- 0.02
- 2015–16
- 0.43
- 2023–24
- 0.01
- Normal
- 0.50
Nov
- 1982–83
- 2.10
- 1997–98
- 1.17
- 2015–16
- 1.54
- 2023–24
- 0.61
- Normal
- 0.79
Dec
- 1982–83
- 1.43
- 1997–98
- 1.35
- 2015–16
- 0.88
- 2023–24
- 0.79
- Normal
- 1.67
Jan
- 1982–83
- 2.10
- 1997–98
- 2.68
- 2015–16
- 3.21
- 2023–24
- 3.65
- Normal
- 1.98
Feb
- 1982–83
- 3.88
- 1997–98
- 7.65
- 2015–16
- 0.05
- 2023–24
- 4.58
- Normal
- 2.20
Mar
- 1982–83
- 6.57
- 1997–98
- 2.21
- 2015–16
- 0.76
- 2023–24
- 2.54
- Normal
- 1.46
Apr
- 1982–83
- 1.74
- 1997–98
- 1.11
- 2015–16
- 0.55
- 2023–24
- 0.16
- Normal
- 0.65
May
- 1982–83
- 0.01
- 1997–98
- 0.64
- 2015–16
- 0.44
- 2023–24
- 0.07
- Normal
- 0.28
Water-year total (Oct–Sep)
- 1982–83
- 18.49
- 1997–98
- 17.16
- 2015–16
- 8.18
- 2023–24
- 12.43
- Normal
- 9.79
Monthly rain in inches at San Diego International Airport (KSAN). Normal is 1991–2020. NOAA Regional Climate Centers ACIS, retrieved Oct 29, 2026. Totals include June–September.
2015–16 is the warning. It was a strong El Niño, and January brought 3.21 inches. Then February brought 0.05 inches. The year ended at 8.18 inches, below the 9.79-inch normal. El Niño tilts the odds toward a wet winter. It doesn't guarantee one.
Why the rain shows up late
El Niño is a warming of the tropical Pacific, and it reaches California through the jet stream. NWS Director Ken Graham said on Oct 16 that a very strong El Niño "will likely bring a southward and eastward shift to the jet stream." The ocean peaks first and the storms follow. NOAA's Climate Prediction Center said on Oct 8 that a strong-to-very strong El Niño is likely through January–March 2027, and its Oct 15 outlook favored above-normal rain for much of California. Daniel Swain of Weather West expects this event to peak in strength most likely in December, with peak California impacts from December through March, and says January and February may bring the highest likelihood of extreme wet conditions.
“What happens this autumn has no bearing whatsoever on what is increasingly likely to occur this coming winter.”
Daniel Swain, Weather West, Oct 12, 2026
What this wet October does and doesn't mean
Rain by Oct 28 vs. the whole year, San Diego airport
| Rain Oct 1–28 | Water-year total | |
|---|---|---|
| 1982–83 | 0.03" | 18.49" |
| 1997–98 | 0.02" | 17.16" |
| 2015–16 | 0.43" | 8.18" |
| 2023–24 | 0.01" | 12.43" |
| 2026–27 | 1.54" | Still to come |
Rain Oct 1–28
- 1982–83
- 0.03"
- 1997–98
- 0.02"
- 2015–16
- 0.43"
- 2023–24
- 0.01"
- 2026–27
- 1.54"
Water-year total
- 1982–83
- 18.49"
- 1997–98
- 17.16"
- 2015–16
- 8.18"
- 2023–24
- 12.43"
- 2026–27
- Still to come
The two wettest years started the driest. The analog with the most October rain, 2015–16, had the smallest winter. Four years is far too few to say an early start hurts. It does show that October tells us almost nothing. Most of this October's 1.54 inches came from Tropical Storm Rachel, a tropical system, not an El Niño winter storm.
San Diego's El Niño calendar
Autumn: little link to El Niño (September to November)
Peak California El Niño impacts (December to March)
Wettest months in 1983 and 1998 (February to March)
- 1OctOct 10–12 · Rachel, 1.04"
- 2NovNov 12 · next CPC ENSO update
- 3DecDec · likely El Niño peak
Peak window from Daniel Swain, Weather West, Oct 12, 2026. Rain-heavy months from NOAA ACIS records at San Diego Intl Airport, 1982–83 and 1997–98.
Is this still right?
We last checked this tip against its sources on October 29, 2026, and we re-research every tip on a schedule. Things in San Diego change, sometimes overnight.
Nature runs on its own schedule: seasons shift with the weather and the ocean, so treat the timing here as typical, not guaranteed.
This is general information, not legal, financial, tax, medical or safety advice.
KEEP READING
SOURCES
Everything above traces back to one of these. Follow them — if one has changed and we haven't, that's our mistake, not yours.
NOAA Regional Climate Centers (ACIS) · 2026-10-29
Retrieved Oct 29, 2026. Same data viewable in NWS NOWData: https://www.weather.gov/wrh/climate?wfo=sgx
NOAA Climate Prediction Center · 2026-10-08
El Niño Advisory; strong-to-very strong El Niño likely through Jan–Mar 2027 (>83% chance). Next discussion Nov 12, 2026.
NOAA Climate Prediction Center · 2026-10-15
Elevated likelihood of above-normal precipitation for much of California and the Southwest (NDJ); West Coast probabilities lower than the Southeast.
Weather West (Daniel Swain) · 2026-10-12
Peak strength likely December; peak California impacts Dec–Mar; little link between autumn rain and El Niño.
KPBS / City News Service · 2026-10-12
Rachel's 72-hour totals, including 1.04" at the airport.
KTVU FOX 2 · 2026-10-16
Ken Graham quote on the jet stream shift.