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San Diego — Monthly Mean Sea Level

Monthly mean sea level at the NOAA tide gauge in San Diego Bay (station 9410170), the longest sea level record in Southern California. Values are in millimeters above or below the station's mean sea level datum for the 1983–2001 tidal epoch.

ArchiveFrom before CK Economics turned to global trade on October 16, 2026. Its figures are still collected and it stays at this address, but it is no longer part of our trade coverage.

Data status: Current
Official statisticCK forecastSource figures as of October 19, 2026 · NOAA station trend + seasonal cycle, 5 years, 80% range of backtest errorsSources & methods
Sources
NOAA Center for Operational Oceanographic Products and Services (CO-OPS)
Period covered
Jan 1906 – Sep 2026
Source figures as of
October 19, 2026
Geography
San Diego Bay tide gauge (NOAA station 9410170)
Sector
Climate Economics & Sustainability (archived)
Seasonal adjustment
Not seasonally adjusted
Transformations
Views other than the level (changes, averages, volatility) are calculated by CK Economics from these figures
Forecast method
NOAA station trend + seasonal cycle
Assumptions
Past patterns continue, with no policy change or shock; fitted to Jan 1906 – Sep 2026
Horizon
5 years
Interval
80% range of backtest errors
Backtest
Errors 40% smaller than repeating the same period a year earlier over the next 3 months, 12% smaller 3–5 years ahead (40 past dates)
Estimated
October 19, 2026
Revisions
Replaced with the source’s latest figures whenever it revises them.
Data status
Current
Limitations
Seasonal swings are left in: compare a period with the same period a year earlier.

Full method · Research standards

Key figures

CK estimateMillimeters · calculated by CK Economics from NOAA Center for Operational Oceanographic Products and Services data

Latest · Sep 2026
333
+185 mm vs a year earlier1
5-year change
+207 mm
since Sep 20212
10-year change
+178 mm
since Sep 20162
Record high
333
Sep 20263
Record low
−281
May 19063
Where the latest ranks
100th pct.
Higher than 100% of the other 1,433 observations since Jan 19064
CK forecast · Sep 2031
164
80% range 131–2325
  1. 1Latest observation against the observation one year earlier (for weekly data, the nearest within three days).
  2. 2Latest observation against the observation five and ten years earlier.
  3. 3Highest and lowest published observations across the full history shown.
  4. 4Share of the other published observations that are lower than the latest one, rounded down.
  5. 5Final period of the CK forecast, a statistical projection from the model in the methodology, with its 80% range; rounded to three significant figures.

Seasonal pattern

CK estimate

Each month of 2026 and 2025 against the average and range of the same month in 2021–2025. Calculated by CK Economics from the published series.

Monthly Millimeters in 2026 and 2025 compared with the 2021–2025 average and range
2026 2025 2021–2025 average 2021–2025 range

Methodology

Each value is NOAA's monthly mean sea level (MSL) at the San Diego tide gauge, the average of the month's hourly water heights, converted from meters to millimeters. Values are relative to the station's MSL datum for the 1983–2001 National Tidal Datum Epoch, so zero is the average sea level over those years. The series is not seasonally adjusted; NOAA's average seasonal cycle puts local sea level about 78 mm above the annual mean in September and about 77 mm below it in April. The record runs from January 1906 to August 2026. NOAA publishes no value for 15 months (January–June 1926 and April–December 1962); these months are left out, not estimated. NOAA marks seven months as inferred (April, October and November 1970, July 1972, April–May 1974 and February 1997), meaning they were estimated from incomplete data rather than fully observed; they are kept as published. The latest month may be based on preliminary data and can change after NOAA's verification. NOAA's long-term relative sea level trend for this station is 2.22 ± 0.08 mm per year (95% confidence) over January 1906 to December 2025, about 0.88 inches per decade or 22 cm per century. This trend combines ocean rise with any vertical land motion at the gauge. Strong El Niño years show up as peaks, such as late 1997 and autumn 2015, the highest months on record. We cross-checked every published month against NOAA's Sea Level Trends monthly means for the station and found identical values, with the same 15 months missing in both. August 2026 was confirmed by averaging that month's 744 hourly water heights from the same API. NOAA may revise figures. Projection: CK Economics statistical projection. The central path comes from NOAA's published linear trend for the station (2.22 mm per year), with the average monthly seasonal cycle and second-order autoregressive errors around it, which capture multi-month anomalies such as El Niño. It extends the historical trend only; it does not include the acceleration in the NOAA 2022 interagency sea level rise scenarios. NOAA's trend is estimated from the whole record, including the years the backtest scores, which flatters its scores slightly. It runs only as far ahead as backtests support: the model is refitted at past dates, its forecasts are scored against what happened, and it is shown only for horizons where its errors were at least 5% smaller than those of the better of a no-change forecast and repeating the same month a year earlier. The shaded band is the 80% range of those backtest errors. It is a conditional estimate that extrapolates past patterns: it does not model policy, tariffs, recessions or other shocks, and it is not an official forecast of the source agency.

How we collect, check and project every dataset →

Source

NOAA Center for Operational Oceanographic Products and Services (CO-OPS), Tides & Currents Data API, monthly mean water levels (station 9410170, San Diego): https://api.tidesandcurrents.noaa.gov/api/prod/datagetter?product=monthly_mean&station=9410170&datum=MSL&units=metric — figures as published on 19 October 2026.

The 60 projected periods are a CK forecast, not figures from the source; the methodology above describes how they are made.

All data

1,434 observations, newest first · Millimeters

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PeriodValueChange y/y
Sep 2026333+185 mm
Aug 2026239+101 mm
Jul 2026189+87 mm
Jun 2026137+47 mm
May 202670+28 mm
Apr 202666+92 mm
Mar 202677+100 mm
Feb 202673+106 mm
Jan 202694+81 mm
Dec 2025118+98 mm
Nov 2025124+94 mm
Oct 2025125+18 mm
Sep 2025148+15 mm
Aug 2025138+13 mm
Jul 2025102+7 mm
Jun 202590+18 mm
May 202542+37 mm
Apr 2025−26−11 mm
Mar 2025−23−33 mm
Feb 2025−33−103 mm
Jan 202513−78 mm
Dec 202420−156 mm
Nov 202430−154 mm
Oct 2024107−102 mm