March 2026
Happy spring in the Northern Hemisphere! There has been a lot to talk about lately climate-wise, from new sea-ice records to global ocean sea surface temperatures surging again to record highs, to summer-like heat across the southwestern United States, and of course, increasingly confident forecasts for a sizable El Niño later in 2026. If you are not up to date on some of these topics, I recommend scrolling back through my social media feeds… it has been a very alarming period. Anyways, this month’s ‘Climate Viz of the Month’ is a bit shorter as I catch up on some rest from last month. Here, I just wanted to quickly highlight a new visualization showing a different way the Arctic has warmed in recent years relative to a historical baseline, along with revealing the types of uncertainties present in station-based surface temperature observational datasets.
Using NOAA’s NOAAGlobalTempv6.1.0 and NASA’s GISTEMPv4 datasets, I have separately plotted the decade of the warmest annual mean temperature for every grid point on the polar stereographic map. Note that these datasets are provided on relatively coarse spatial grids, which is why the “boxes” are quite visible in the plot rather than showing smoother contours with finer spatial features. To produce this map, I considered all available years in each dataset (beginning in either 1850 or 1880), calculated annual means, and then ranked these values independently at each latitude and longitude point. Rather than go into all of the technical differences between these two observational datasets (see the Climate Data Guide for summaries: NASA vs. NOAA), it is important to note that they use different approaches for spatial interpolation and infilling, which becomes especially relevant in the polar regions where in situ observations from weather stations and buoys are sparse. I should also point out that NOAA’s product was recently updated from v6 to v6.1 this year, and not that long ago it did not even provide temperature coverage across large portions of the polar regions.
Comparing these two visualizations reveals some striking (though largely unsurprising) similarities, particularly in the broad-scale patterns of where the warmest decades have occurred. Across much of the Arctic Ocean, the warmest conditions are most often found in the 2010s, while over parts of Siberia they more frequently occur in the 2020s. There are some small differences between the datasets at individual grid points, especially near the edge of the Arctic Circle (white dashed line), reflecting differences in data input coverage and interpolation. However, the overall climate signal is clear: for nearly all locations, the warmest years on record have occurred within the past two decades, even when considering the full historical record back to the mid/late 19th century. Another key takeaway is that uncertainties in Arctic temperature estimates can be substantial, particularly in data-sparse regions, which reinforces the importance of comparing multiple datasets rather than relying on any single product (including for using atmospheric reanalysis). Continued research and sustained support are critical for maintaining and improving these observational records, especially as the Arctic continues to change rapidly. Now onto my summary of the region from last month…
March was a historic month for temperatures across the Northern Hemisphere, especially over the United States. Farther north, the pattern was also striking, with unusually sharp contrasts: record-breaking warmth over the contiguous U.S., anomalous cold over Canada and Alaska, and more anomalous warmth across the northernmost Arctic. While March 2026 certainly did not rank among the warmest Arctic-wide monthly means, there were notable regional extremes. In fact, temperatures were statistically tied for the warmest on record near the North Pole, as well as across the Barents Sea region and near Svalbard. In these areas, anomalies exceeded 5°C above the 1981-2010 average, extending from the Greenland Sea across the Arctic and into eastern Siberia. Meanwhile, temperatures were more than 5°C below average over the Kara Sea and western Siberia, along with northern land areas of North America, where monthly mean near-surface air temperatures in some locations remained below -30°C.
Arctic sea-ice extent remained unusually low and was statistically tied for the lowest on record for March. This follows the new record low for the annual maximum set earlier this year, breaking the previous record from 2025, which I discussed in last month’s blog.
Two technical notes for this month’s Arctic recap, both tied to the decommissioning of the NCEP/NCAR R1 reanalysis. One of my earliest visualizations I created (I think from back when I was in grad school) showed a ranking plot using 925 hPa temperatures from NCEP/NCAR R1 to track how warm or cold each Arctic month has been since 1979. I chose 925 hPa in part because R1 has known limitations in representing Arctic boundary layer temperatures, and because surface values can be influenced by heat flux exchanges, especially near sea-ice anomalies and around the marginal ice zone. With R1 now retired, I have transitioned this visualization to ECMWF’s ERA5 and will continue updating it in near-real time on my Arctic Temperature page. The original R1 version remains available on my website for archival purposes though. You may notice some differences in exact rankings between ERA5 and R1, which is expected given improvements in data assimilation and reanalysis-model physics, along with persistent observational gaps in the Arctic, such as the limited radiosonde coverage. Despite this, the agreement is better than I expected, and the long-term warming patterns are very similar.
Finally, we are still missing an update from PIOMAS this month for Arctic sea-ice thickness and volume (and GIOMAS for the Antarctic). I have not yet identified a workaround while we await further updates to the model (see last month’s blog for more details). In addition, the merged satellite-derived product from CryoSat-2/Sentinel-3/SMOS has issued its final thickness update for the season and will resume in the fall. Even so, all available evidence suggests that mean Arctic sea-ice thickness remains near historic lows.
Thank you for reading! You can find archives of my past blogs since 2022 listed below. If you would like to support the development and maintenance of this website, I have a Buy Me a Coffee page at: https://buymeacoffee.com/zacklabe.
Changes in mean surface air temperature anomalies (GISTEMPv4; 1951-1980 baseline), mean Arctic sea ice extent (NSIDC; Sea Ice Index v4), and mean Arctic sea ice volume (PIOMAS v2.1; Zhang and Rothrock, 2003) over the satellite era. Updated 4/17/2026.
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[2] Witt, J.K., Z.M. Labe, A.C. Warden, and B.A. Clegg (2023). Visualizing uncertainty in hurricane forecasts with animated risk trajectories. Weather, Climate, and Society, DOI:10.1175/WCAS-D-21-0173.1
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[1] Witt, J.K., Z.M. Labe, and B.A. Clegg (2022). Comparisons of perceptions of risk for visualizations using animated risk trajectories versus cones of uncertainty. Proceedings of the Human Factors and Ergonomics Society Annual Meeting, DOI:10.1177/1071181322661308
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The views presented here only reflect my own. These figures may be freely distributed (with credit). Information about the data can be found on my references page and methods page.