Ocean · oscillations
The great pendulums of climate
Four indices describe modes of variability: the PDO in the North Pacific, the AMO in the North Atlantic, the Arctic Oscillation over the pole, and the NAO between the Icelandic Low and the Azores High. Each region takes the colour of its latest value.
- Positive phase
- Negative phase
Latest PDO
-1.55
Latest NAO
0.53
Latest AO
1.16
Latest AMO (unsmoothed)
0.192 °C
Pacific Decadal Oscillation index (NCEI, ERSSTv5) · U.S. Government work, public domain · 10/23/26
North Atlantic Oscillation index (NOAA CPC) · U.S. Government work, public domain · 10/23/26
Arctic Oscillation index (NOAA CPC) · U.S. Government work, public domain · 10/23/26
Atlantic Multidecadal Oscillation, unsmoothed (NOAA PSL, Kaplan SST) · U.S. Government work, public domain · 10/23/26
Schematic regions; colour from the latest value of each index (NAO: sign inverted over Iceland, where pressure falls in the positive phase).
Latest PDO
-1.55
2026-09
provisional value
Pacific Decadal Oscillation index (NCEI, ERSSTv5) · U.S. Government work, public domain · 10/23/26
Latest NAO
0.53
2026-09
provisional value
North Atlantic Oscillation index (NOAA CPC) · U.S. Government work, public domain · 10/23/26
Latest AO
1.16
2026-09
provisional value
Arctic Oscillation index (NOAA CPC) · U.S. Government work, public domain · 10/23/26
Latest AMO (unsmoothed)
0.192 °C
2023-01
provisional value
Atlantic Multidecadal Oscillation, unsmoothed (NOAA PSL, Kaplan SST) · U.S. Government work, public domain · 10/23/26
Pacific Decadal Oscillation since 1854, yearly mean
Pacific Decadal Oscillation index (NCEI, ERSSTv5) · U.S. Government work, public domain · 10/23/26
Show the data as a table
Atlantic Multidecadal Oscillation since 1856, yearly mean
Atlantic Multidecadal Oscillation, unsmoothed (NOAA PSL, Kaplan SST) · U.S. Government work, public domain · 10/23/26
Show the data as a table
Monthly NAO and AO since 2000
North Atlantic Oscillation index (NOAA CPC) · U.S. Government work, public domain · 10/23/26
Arctic Oscillation index (NOAA CPC) · U.S. Government work, public domain · 10/23/26
Show the data as a table
NAO since 1950, yearly mean
North Atlantic Oscillation index (NOAA CPC) · U.S. Government work, public domain · 10/23/26
Show the data as a table
Method and sources
Monthly indices read as published: PDO from NOAA NCEI (ERSSTv5, 1854–), NAO and AO from the Climate Prediction Center (1950–), unsmoothed AMO from PSL (Kaplan SST, 1856–2023). Yearly means are computed on the server; no additional smoothing or detrending is applied.
The last two months are flagged provisional.
Reading these data
These indices describe modes of internal variability; their “periodicity” is irregular and their predictability limited. The undetrended AMO includes global warming; definitions differ between providers.
SOURCES OF THIS PAGE
- Pacific Decadal Oscillation index (NCEI, ERSSTv5)
-
NOAA NCEI, PDO index from ERSSTv5 (leading PC of North Pacific SST anomalies poleward of 20°N, global mean removed), 1854–.
· source page ↗
Licence : U.S. Government work, public domain · retrieved on Oct 23, 2026 · SHA-256 4fd8857f51d6… - North Atlantic Oscillation index (NOAA CPC)
-
NOAA CPC, monthly North Atlantic Oscillation index (rotated PCA of 500 hPa height anomalies, 1950–).
· source page ↗
Licence : U.S. Government work, public domain · retrieved on Oct 23, 2026 · SHA-256 1d4c1cdcc5d0… - Arctic Oscillation index (NOAA CPC)
-
NOAA CPC, monthly Arctic Oscillation index (projection of 1000 hPa height anomalies onto the leading EOF, 1950–).
· source page ↗
Licence : U.S. Government work, public domain · retrieved on Oct 23, 2026 · SHA-256 cdbee5966af8… - Atlantic Multidecadal Oscillation, unsmoothed (NOAA PSL, Kaplan SST)
-
NOAA PSL, AMO index (unsmoothed, from the Kaplan SST V2, North Atlantic 0–70°N), after Enfield et al. (2001).
· doi:10.1029/2000GL012745 · source page ↗
Licence : U.S. Government work, public domain · retrieved on Oct 23, 2026 · SHA-256 9bf4d13f5c69…