NOAA CPC ENSO Climate Indices

NOAA CPC ENSO Climate Indices

NOAA's Climate Prediction Center (CPC) publishes a page of Monthly Atmospheric & SST Indices as keyless plain-text ASCII files, including the Oceanic Niño Index (ONI), Southern Oscillation Index (SOI) and a series captioned on the page "(Relative Oceanic Nino Index)" (RONI).

Coverage

The ONI file (oni.ascii.txt, captioned on the page "(Oceanic Nino Index)") lists 3-month running-mean Niño 3.4 sea surface temperature anomalies by season and year; fetched 2026-11-11, its rows ran from DJF 1950 through ASO 2026. The page also lists other monthly and seasonal atmospheric and sea-surface-temperature index series (Niño regions, Darwin/Tahiti sea-level pressure, outgoing longwave radiation and related measures). A page-wide update cadence is Not stated beyond the individual Monthly/Seasonal labels used for each series.

Verdict

Keyless plain-text ENSO and related climate-index time series from NOAA's Climate Prediction Center — the Oceanic Niño Index (ONI), Southern Oscillation Index (SOI), a Relative ONI series and other monthly/seasonal atmospheric and SST indices. Licensed Custom: NWS's disclaimer says "The information on National Weather Service (NWS) Web pages are in the public domain, unless specifically noted otherwise, and may be used without charge for any lawful purpose so long as you do not: 1) claim it is your own (e.g., by claiming copyright for NWS information -- see below), 2) use it in a manner that implies an endorsement or affiliation with NOAA/NWS, or 3) modify its content and then present it as official government material." Rate limits: Not stated. Signal Lab links only.