A monthly reporting on mean sea surface temperatures and marine heatwave conditions.
Key takeaways
- February 2025 was the 2nd warmest February on record for the global ocean, with a mean temperature of 20.95 ± 0.08 °C.
- The past month was the warmest February on record for the Mediterranean Sea (16.41 ± 0.12 °C).
- In the European Zone, February 2025 experienced the largest marine heatwave geographical extent of the past year.
Sea Surface Temperature
Figure 1: Daily sea surface temperatures (SST) averaged for the global ocean (top), the Mediterranean Sea (left) and the North Atlantic Ocean (right) between 1991-2020 using ESA’s Climate Change Initiative (grey shades), and between 2021-2025 (colored shades) using Mercator Ocean International’s GLO12 analysis and forecast.
- February 2025 was the 2nd warmest February on record (after 2024), with a mean sea surface temperature (SST) of 20.95 ± 0.08 °C (against 21.11 ± 0.04 °C for 2024) at the global level (between 60°S and 60°N).
- For the Mediterranean Sea, was the warmest February month with mean temperatures of 16.41 ± 0.12 °C.
- For the North Atlantic, was the 2nd warmest February month (after 2024) with mean temperatures of 20.48 ± 0.12 °C.
Sea Surface Temperature Anomalies
- Mean sea surface temperature anomalies (Figure 2) for February 2025 are close to 1°C in the Caribbean Sea, the North Atlantic, the Southern Ocean (between 30°E and 150°E) and the southeast Asia region.
- Mean anomalies range between 1 and 2°C east of Madagascar, in the Mediterranean Sea and off the Chileancoast. Mean anomalies are higher in the southern Pacific off New Zeeland on the east, west Australia and in the Kuroshio region and its extension in the Pacific, reaching 3°C locally.
- In the Tropical Pacific, negative anomalies are still present on the equator, reaching -1°C.
Ongoing marine heatwaves: 28 February 2025
Long warming events may induce important stress on marine ecosystems. In this section are shown the ongoing marine heatwave (MHW) events on February 28, and when those have initiated.
- 27% of the global ocean (between 60°S and 60°N) were affected by MHWs on the 28th of February.
- The majority of these MHWs developed recently, with 18 % of the global Ocean (between 60°S and 60°N) affected by MHWs less than 1 month old and 7 % by events between 1- and 2-month-old.
- 2 % of the global ocean is affected by 2 to 4-month-old events.
Total surface exposed to marine heatwaves: March 2024 – February 2025
We monitor daily the surface occupied by MHWs and show for the past year (since March 2024) the proportion of the global Ocean (between 60°S and 60°N) exposed to MHWs. We focus on the evolution over the past February 2025 (denoted in grey).
Global Ocean
- In February, the total surface of MHW (black line) was stable across the month with values between ~25% and 27%.
- Surface of moderate category (yellow line) follows the same pattern around 22%; whereas surface of strong category (orange line) slightly decreases during the month (from ~5% to ~3.5%).
- For comparison, in February 2024, MHW total extent ranged between ~40% and ~35%, with almost 10% of strong category (not shown).
European Zone
- For the ocean region of Europe (including the Mediterranean Sea and the North Atlantic eastern coast, in figure 3) the total MHW surface ranged between 36% and 39% with an overall increase during the month (from 37% to 39%).
- February 2025 experienced the highest MHW extent since March 2024. MHWs were mostly composed of moderate and strong categories (~31% and ~6%, respectively).
- For comparison, in February 2024, the total MHW extent was ~28% with a peak at 34%.
Total number of marine heatwave days for February 2025
16% of the surface of the ocean was impacted by strong, or higher, MHW conditions for at least 1 day. North Papua New Guinea, east Madagascar and the southern Pacific off New Zealand and off Chili are the most affected.
Figure 6: Number of days during which a MHW of category strong, severe or extreme occurred in February 2025. Blank areas mean that no MHW of strong or higher category happened during the month.
February Statistics
Figure 7: MHW characteristics for February months from 1993 to 2025. Duration, intensity, extent and activity averaged for each February month between 1993 and 2025 for the global ocean (left), for the Mediterranean Sea (centre) and the North Atlantic Ocean (right). February 2025 is highlighted with a blue edge.
The MHW statistics (duration, intensity, surface occupied and activity) for February 2025 are compared to those for February months from previous years (since 1993).
- On a global scale, February 2025 is the 3rd most extreme February month in terms of duration and intensity after 1998 and 2024.
- In the Mediterranean Sea, February 2025 was the 3rd most extreme February in terms of MHW activity, after 2011 and 2024.
- In the North Atlantic, February 2025 was the 2nd most extreme February month in terms of surface and duration, lower than February 2024 that showed record mean intensity, duration and total activity.
About the bulletin
Mercator Ocean International (MOi) publishes a monthly sea surface temperature bulletin reporting on mean temperature and marine heatwave conditions for the month just passed. It includes:
- Regions where MHWs are present and the time these events started,
- Timeseries showing the total surface occupied by MHWs globally and for the European region,
- The total number of days of exposure to MHW during the month (including only strong and higher intensity categories).
Image citation: European Union, Copernicus Marine Service Data 2024 I © Mercator Ocean
All images in this article can be used freely and should be cited with the information above.
Datasets and Products
Sea Surface Temperature
The results are obtained using the Copernicus Marine Service global analysis and forecasting system together with observation-based products.
- GLOBAL_ANALYSISFORECAST_PHY_001_024 Global Ocean Physics Analysis and Forecast sea surface temperature. E.U. Copernicus Marine Service Information. Marine Data Store (MDS). DOI: https://doi.org/10.48670/moi-00016
- ESA SST CCI reprocessed sea surface temperature analyses. E.U. Copernicus Marine Service Information. Marine Data Store (MDS). DOI: https://doi.org/10.48670/moi-00169
- NOAA OI SST V2 High Resolution Dataset data provided by the NOAA PSL, Boulder, Colorado, USA, from their website at https://psl.noaa.gov, Huang, B., C. Liu, V. Banzon, E. Freeman, G. Graham, B. Hankins, T. Smith, and H.-M. Zhang, 2021:
- Improvements of the Daily Optimum Interpolation Sea Surface Temperature (DOISST) Version 2.1, Journal of Climate, 34, 2923-2939. doi: 10.1175/JCLI-D-20-0166.1
- Global Ocean OSTIA Sea Surface Temperature and Sea Ice Analysis. E.U. Copernicus Marine Service Information. Marine Data Store (MDS). DOI: https://doi.org/10.48670/moi-00165
- ODYSSEA Global Sea Surface Temperature Gridded Level 4 Daily Multi-Sensor Observations. E.U. Copernicus Marine Service Information. Marine Data Store (MDS). DOI: https://doi.org/10.48670/moi-00016
Notes: The global analysis system was used to study the ocean surface temperature from 2021 and 2025. To study surface temperature for previous years (1991 to 2020), it was used the ESA CCI data. The other observation-based sea surface temperature products (OSTIA, OI SST and Odyssea) were used for calculating monthly mean and uncertainty values for February 2025.
Marine Heatwaves
The results are obtained using the Copernicus Marine Service global systems including the analysis and forecasting system together with the reanalysis product.
- GLOBAL_ANALYSISFORECAST_PHY_001_024 Global Ocean Physics Analysis and Forecast sea surface temperature. E.U. Copernicus Marine Service Information (CMEMS). Marine Data Store (MDS). DOI: https://doi.org/10.48670/moi-00016
- GLOBAL_MULTIYEAR_PHY_001_030 Global Ocean Physics Reanalysis sea surface temperature. E.U. Copernicus Marine Service Information (CMEMS). Marine Data Store (MDS). DOI: https://doi.org/10.48670/moi-00021
Notes: The global analysis system was used to study MHWs for 2024 and 2025. To study MHWs for previous Februarys (1993 to 2023), it was used the reanalysis system. The reanalysis product was used for generating a daily climatology using the 30-year period from 1993 to 2022.
