Marine Heatwaves


Marine heatwaves are periods of persistent anomalously warm ocean temperatures, which can have significant impacts on marine life as well as coastal communities and economies. Scientists at PSL are working to characterize marine heatwaves, understand how they form and dissipate, and predict them in advance. On this page, we will provide current ocean maps, forecasts of heatwaves, interactive tools for users to explore ocean heatwaves themselves, links to research results and to webpages at other institutions.

To reference plot in a publication, please cite as "Image provided by the NOAA Physical Sciences Laboratory, Boulder, Colorado from the website at ".

Q&A for the interactive tool

  • How to interact with the map
  • What is a percentile and how is it used to define a MHW
  • Why does the sea surface temperature (SST) trend matter
  • How to interact with the time series
  • What are the rankings

Further questions please contact

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To reference plot in a publication, please cite as "Image provided by the NOAA Physical Sciences Laboratory, Boulder, Colorado from the website at ".

Q&A for the forecast tool

  • How to interact with the map
  • What is marine heatwave
  • Why does the sea surface temperature (SST) trend matter
  • What is prediction skill

Further questions please contact

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High Resolution Ocean Surface Condition

User Options

Dataset* :
Region :
Frequency :
Statistic :
Year* :
Month* :
Day* :

(LMEs) map showing the associated ID number and name.

* availibility for date (year, month, day) options.

Creating Plot ⏳


Web Based Tools for looking at Marine Heatwaves

PSL has several web-based tools for plotting and analyzing gridded datasets and timeseries. With these tools, you can extract time-series from different regions, plots maps of means and anomalies, create correlations maps, and analysis time-series. We are also expanding upon what these tools can do.

List of tools

  • WRIT Ocean Maps and Vertical Crossections

    Allows users to make maps and vertical cross-sections from various reanalyses. Statistics include means, anomalies and climatologies. Users can also difference the various reanalyses for all three types of statistics (for any overlapping date in the reanalyses). Composites (averaging multiple dates) are also available.

  • WRIT Ocean Time-series Extraction and Analysis
  • Extracts timeseries at specified latitude/longitude or latitude/longitude ranges and either plots the time-series, time-series differences, and scatter plots. Various statistics are returned in addition to numeric values of the time-series plotted. Ability to plot and compare climate index time-series such as the PNA or Niño3.4 or upload your own.

  • WRIT Ocean Correlation Maps Vertical Crossections.

    Calculates correlations (and regressions) of the reanalysis and observational dataset with supplied atmospheric/ocean indices or user uploaded time-series. Users can plot correlations at different lead/lags. They can also create vertical cross-section correlation plots.

PSL Publications

Refereed Papers

  • Jacox, M. G., M. A. Alexander, D. J. Amaya, E. Becker, S. J. Bograd, S. Brodie, E. L. Hazen, M. Pozo Buil, and D. Tommasi (2022): Global seasonal forecasts of marine heatwaves, Nature, 604, 486-490,
  • A. Capotondi, M. Newman, Xu, T., and E. Di Lorenzo (2022): An Optimal Precursor of Northeast Pacific Marine Heatwaves and Central Pacific El Niño Events, Geophys. Res. Lett., 49 (5), e2021GL097350,
  • Amaya, D. J., M. A. Alexander, A. Capotondi, C. Deser, K. Karnauskas, A. J. Miller and N. Mantua (2021): Are Long-Term Changes in Mixed Layer Depth Influencing North Pacific Marine Heatwaves?. Bull. Amer. Meteor. Soc., 102 (1), S59-S66,
  • Xu, T., M. Newman, A. Capotondi and E. Di Lorenzo (2021): The Continuum of Northeast Pacific Marine Heatwaves and Their Relationship to the Tropical Pacific. Geophys. Res. Lett., 48 (2), 202GL090661,
  • Jacox, M. G., M. A. Alexander, S. J. Bograd and J. D. Scott (2020): Thermal displacement by marine heatwaves. Nature, 584, 82-86,
  • Jacox, M. G., D. Tommasi, M. A. Alexander, G. Hervieux and C. A. Stock (2019): Predicting the Evolution of the 2014–2016 California Current System Marine Heatwave From an Ensemble of Coupled Global Climate Forecasts. Front. Mar. Sci., 6, 497,
  • Alexander MA, JD Scott, KD Friedland, KE Mills, JA Nye, AJ Pershing, AC Thomas, (2018): Projected sea surface temperatures over the 21st century: Changes in the mean, variability and extremes for large marine ecosystem regions of Northern Oceans. Elementa: Science of the Anthropocene, 6(1):9,
  • Scannell, H. A., A. J. Pershing, M. A. Alexander, A. C. Thomas and K. E. Mills (2016): Frequency of marine heatwaves in the North Atlantic and North Pacific since 1950. Geophys. Res. Lett., 43 (5), 2069-2076,

Marine Heatwave Related Datasets

Marine Heatwave Forecast

The forecast generated by Jacox et al., 2022

SST Datasets at PSL

Ocean Reanalyses at PSL

Ocean Time-series at PSL



  • The California Current Marine Heatwave Tracker
    Developed by oceanographers from NOAA Fisheries’ Southwest Fisheries Science Center as an experimental tool for natural resource managers, the California Current MHW Tracker is a program designed to understand, describe, and provide a historical context for the 2014-16 blob.2 It also produces a range of indices that could help forecast or predict future MHWs expected to impact the CA coast.(NOAA Integrated Ecosystem Assessment)
  • So What are Marine Heatwaves?
    NOAA research scientist explains what marine heat waves are and their impacts. (NOAA Research News)
  • Marine Heatwaves Organization
    From the Marine Heatwaves International Working Group which is dedicated to ​understanding marine heatwaves: their physical drivers, climatological properties, and ecological impacts. The webpage summarizes their research. (
  • Marine Heatwave: Wikipedia
    A definition of marine heatwaves, potential drivers, and a list of some past strong marine heatwaves throughout the globe.(Wikipedia)
  • Scripps: California's Marine Heatwaves FAQ
    Explore this FAQ to learn more about what’s causing marine heat waves and their impacts in California.(UC San Diego/Scripps)
  • Climate Central: Ocean HeatwavesKey concepts about marine heatwaves with an emphasis on heatwaves and climate change.
    (Climate Central)
  • NOAA Blog: ENSO and Marine HeatwavesA an interview with two PSL scientists about marine heatwaves, what causes them, how they are impacted by ENSO and how climate change might impact their frequency, among other topics. (
  • Looking back at the BLOB: Marine Heatwave
    A history of the development of and the demise of the famous "Blob", the 2015-16 heat wave in the NE Pacific ocean. (NOAA Fisheries News).
  • NOAA research shows promise for predicting marine heatwaves
    A news article about the possibility of predicting marine heatwaves successfully. (NOAA Research News).


  • Python code that defines marine heatwaves from SST data


This is a Research and Development Application