Climate Indices

Climate indices are simple diagnostic quantities that are used to characterize an aspect of a geophysical system such as a circulation pattern. They track droughts, ENSO events, wind patterns, internal modes of climate variability, and extreme events like wildfires and heatwaves. Climate indices play a key role in climate monitoring and prediction. The climate index overview page summarizes the philosophy of climate indices.

To find a specific climate index, jump to the search box below or click your desired index from among the blue sub-category buttons.

To see only the indices with in-depth commentary, select the "Datasets with guidance" button when using the search box.

Dataset Overviews

Climate datasets

Has expert guidance
Marshall Southern Annular Mode (SAM) Index (Station-based) Marshall Southern Annular Mode (SAM) Index (Station-based)

  • Years of Record

  • 1957-01 to 2015-09

The station-based index of the Southern Annular Mode (SAM) is based on the zonal pressure difference between the latitudes of 40S and 65S.  As such, the SAM index…

Main variables and Earth System components

Atmosphere Sea Level Pressure
Southern Hemisphere westerly jet strength and position Southern Hemisphere westerly jet strength and position

  • Years of Record

  • 1979-12 to 2016-12

The dynamics of the Southern Hemisphere westerly jet are described in terms of two indices, jet strength and jet latitude.  Here, these indices are defined using the…

Main variables and Earth System components

Atmosphere Wind
Standardized Precipitation Evapotranspiration Index (SPEI) Standardized Precipitation Evapotranspiration Index (SPEI)

  • Years of Record

  • 1901-01 to 2014-03

The Standardized Precipitation Evapotranspiration Index (SPEI) is an extension of the widely used Standardized Precipitation Index (SPI). The SPEI is designed to take into…

Main variables and Earth System components

N/A

    • Timestep

    • Monthly, Seasonal, Annual

    • Collections

    • N/A
Drought atlases from tree rings Drought atlases from tree rings

  • Years of Record

  • 0000-01 to 2005-12

Tree-ring drought atlases provide a paleoclimate analog to modern drought indices, most commonly the Palmer Drought Severity Index (PDSI).  Produced on a regular lat-…

Main variables and Earth System components

Land Drought
Standardized Precipitation Index (SPI) Standardized Precipitation Index (SPI)

  • Years of Record

  • 1949-01 to 2018-07

The Standardized Precipitation Index (SPI) is a widely used index to characterize meteorological drought on a range of timescales. On short timescales, the SPI is closely…

Main variables and Earth System components

Atmosphere Precipitation Land Drought

    • Formats

    • N/A

    • Timestep

    • Monthly

    • Domain

    • N/A

    • Collections

    • N/A
Map of linear trend in R99p https://www.metoffice.gov.uk/hadobs/hadex3/images/HadEX3_R99p_1901-2018_ADW_61-90_1.25x1.875deg_Ann_trend.png HadEX3: Gridded Temperature and Precipitation Climate Extremes Indices (CLIMDEX data)

  • Years of Record

  • 1901-01 to 2018-12

HadEX3 provides gridded, station-based indices of temperature- and precipitation- related climate extremes and supersedes HadEX2. It is intended for global and continental…

Main variables and Earth System components

Atmosphere Air Temperature at 2m Maximum Air Temperature Minimum Air Temperature Land Freeze/Thaw
Nino SST Indices (Nino 1+2, 3, 3.4, 4; ONI and TNI) Nino SST Indices (Nino 1+2, 3, 3.4, 4; ONI and TNI)

  • Years of Record

  • 1870-01 to 2023-04

There are several indices used to monitor the tropical Pacific, all of which are based on sea surface temperature (SST) anomalies averaged across a given region. …

Main variables and Earth System components

Ocean SST - sea surface temperature
Palmer Drought Severity Index (PDSI) Palmer Drought Severity Index (PDSI)

  • Years of Record

The Palmer Drought Severity Index (PDSI) uses readily available temperature and precipitation data to estimate relative dryness. It is a standardized index that generally…

Main variables and Earth System components

Land Drought
Meridional Modes and their indices Meridional Modes and their indices

  • Years of Record

In each of the world’s tropical ocean basins, year-to-year climate variability is primarily governed by fluctuations in the zonal sea surface temperature (SST) gradient and…

Main variables and Earth System components

Atmosphere Wind Ocean SST - sea surface temperature
timeseries of signal and noise in the SOI Southern Oscillation Indices: Signal, Noise and Tahiti/Darwin SLP (SOI)

  • Years of Record

  • 1866-01 to 2025-03

The Southern Oscillation Index (SOI) is a time series used to characterize the large scale sea level pressure (SLP) patterns in the tropical Pacific. Monthly mean SLP at…

Main variables and Earth System components

Atmosphere Sea Level Pressure
NSIDC Sea Ice Index NSIDC Sea Ice Index

  • Years of Record

  • 1978-10 to 2022-01

The NSIDC Sea Ice Index is a suite of easy-to-use sea ice analyses to track changes in Arctic and Antarctic sea ice. The product is produced and supported by the NOAA at…

Main variables and Earth System components

Cryosphere Sea Ice Concentration
The NAM (or Arctic Oscillation) is defined as the first EOF of NH (20°-90°N) winter SLP data. It explains 23% of the extended winter mean (December-March) variance, and it is clearly dominated by the NAO structure in the Atlantic sector. Hurrell wintertime SLP-based Northern Annular Mode (NAM) Index

  • Years of Record

  • 1899-01 to 2025-03

The NAM (or Arctic Oscillation) is defined as the first EOF of NH (20°-90°N) winter SLP data. It explains 23% of the extended winter mean (December-March) variance, and it…

Main variables and Earth System components

Atmosphere Sea Level Pressure
Amundsen Sea Low indices Amundsen Sea Low indices

  • Years of Record

  • 1959-01 to 2022-12

The Amundsen Sea Low (ASL) is a climatological low pressure center located over the extreme southern Pacific Ocean, off the coast of West Antarctica.  Atmospheric…

Main variables and Earth System components

Atmosphere Sea Level Pressure
GHCNDEX: Gridded Temperature and Precipitation Climate Extremes Indices (CLIMDEX data) GHCNDEX: Gridded Temperature and Precipitation Climate Extremes Indices (CLIMDEX data)

  • Years of Record

  • 1951-01 to 2014-02

GHCNDEX provides gridded, station-based indices of temperature- and precipitation- related climate extremes. It is intended for detection and attribution studies, climate…

Main variables and Earth System components

Atmosphere Maximum Air Temperature Minimum Air Temperature Land Freeze/Thaw

  • Experts contributing reviews

  • N/A
HadEX2: Gridded Temperature and Precipitation Climate Extremes Indices (CLIMDEX data) HadEX2: Gridded Temperature and Precipitation Climate Extremes Indices (CLIMDEX data)

  • Years of Record

  • 1901-01 to 2010-12

Note: HadEX2 has been superseded by HadEX3. HadEX2 provides gridded, station-based indices of temperature- and precipitation- related climate extremes. It is intended for…

Main variables and Earth System components

Atmosphere Maximum Air Temperature Minimum Air Temperature Land Freeze/Thaw

  • Experts contributing reviews

  • N/A
U.S. Climate Extremes Index (CEI) U.S. Climate Extremes Index (CEI)

  • Years of Record

  • 1910-01 to 2019-11

The U.S. Climate Extremes Index (CEI) was first presented in 1995 as a framework for quantifying observed changes in climate within the contiguous United States. At…

Main variables and Earth System components

Atmosphere Air Temperature Maximum Air Temperature Minimum Air Temperature Precipitation Wind Land Drought
Overview: Climate Indices Overview: Climate Indices

  • Years of Record

A climate index is a simple diagnostic quantity that is used to characterize an aspect of a geophysical system such as a circulation pattern. A variety of methods have been…

Main variables and Earth System components

Atmosphere Ocean

  • Experts contributing reviews

  • N/A
Asymmetry and Diversity in the pattern, amplitude and duration of El Niño and La Niña Asymmetry and Diversity in the pattern, amplitude and duration of El Niño and La Niña

  • Years of Record

El Niño and La Niña, the two phases of ENSO, are sometimes described as opposites. However, there are asymmetries in their spatial structure, amplitude, duration and…

Main variables and Earth System components

Ocean SST - sea surface temperature

    • Formats

    • N/A

    • Timestep

    • N/A

    • Collections

    • N/A