Dear Arctic Science and Sea Ice Community,

The Sea Ice Prediction Network (SIPN) invites you to contribute to the September 2026 Sea Ice Outlook (SIO)—a collaborative, community-driven effort to improve and compare seasonal sea ice forecasts. Whether you are a returning contributor or new to the Outlook, your input is highly valued. Please share this call with colleagues, collaborators, or research groups who may be interested in participating.

Questions? Contact the SIO team at seaiceoutlook@gmail.com

Call for Contributions: September 2026 Sea Ice Outlook (Based on May Data)

Submission Deadline: 6:00 p.m. AKDT | Wednesday, 10 June 2026

The Sea Ice Outlook (SIO) offers a platform for researchers and forecasters to share predictions of September Arctic sea-ice extent and related variables. Following each month's collection of contributions, key visualizations (including pan-Arctic sea ice forecast figures) will be published by month on the SIO website. A Post-Season Report, focusing on June-September forecast accuracy and performance compared to the observed minimum, is planned for release after the melt season.

The 2026 SIO is supported by the NOAA Global Ocean Monitoring and Observing Arctic Research Program (GOMO-ARP). 

The 2026 SIO solicitation is the same as 2025—contributors are asked to submit a new outlook for each month of the melt season (June-September). No submitted outlooks will be automatically carried forward from one month to the next. For example, please do not submit outlooks developed in July (based on June and July data only) to the August SIO. (See the tentative schedule linked below.)

JUNE SUBMISSION DEADLINE: 6:00 p.m. AKDT, Wednesday 10 June 2026

• Contributions received after the deadline may not be fully incorporated into the Outlook figures.

• Questions, including how to submit contributions that may not fit into one of the requested formats below, may be directed to the SIO team at seaiceoutlook@gmail.com.

Sea Ice Outlook data resources are available via the National Snow and Ice Data Center (NSIDC) SIPN Data Set webpage.

The 2026 SIO Solicitation Requests:

• Outlooks for pan-Arctic, pan-Antarctic, and Alaskan regional September monthly mean sea-ice extent, related uncertainty/probability estimates, and the optional submissions of sea-ice extent anomaly forecasts. We particularly encourage submissions for the Alaska region (i.e., Bering, Chukchi, and Beaufort seas).

• Full Field of Sea Ice Forecasts:

  1. Estimates of Sea Ice Probability (SIP), defined as the fraction of ensemble members in an ensemble forecast with September ice concentration in excess of 15%.

  2. Estimates of Ice-Free Dates (IFD), defined as the first day that Sea Ice Concentration (SIC) drops below 15% ('IFD15'). A second metric we invite is the IFD calculated for an 80% SIC threshold ('IFD80').

  3. For August and September only: estimates of Ice Advance Dates (IAD), defined as the first date (quantified as day of year) in the freeze up season (i.e., after the summer minimum) at which ice concentration first increases over 15% ('IAD15') and over 80% ('IAD80').

• Spatial fields of forecast's initial conditions, particularly sea ice concentration and sea ice thickness or ice thickness distribution, with the date of initialization documented. If forecasts are produced from multiple initializations, these could be the mean fields across your initializations or you can include each single initialization.

• Supplemental materials, including PDFs of any additional figures and/or text files,

Note: All participants whose methods provide information at the regional scale are again encouraged to provide full spatial fields. These submissions will allow organizers to compute metrics such as sea ice probability and first ice-free day for contributors, as well as additional regional analysis for the Sea Ice Outlook. (See submission instructions below.)

2026 Submission Instructions

Instructions for Submitting Pan-Arctic, Pan-Antarctic, and Alaska Regional Outlooks

Contributors should use the June Online Submission Form to submit:

• Required core information for pan-Arctic Outlook projections using dynamical model, statistical, heuristic, and mixed methods. To be consistent with observations from the NSIDC Sea Ice Index extent, compute the total extent (sum of cell areas >15%) for each day and then average the extents from each of the days in the month into a monthly average extent.

• Information for pan-Antarctic and/or Alaska regional sea ice extent projections using dynamical model, statistical, heuristic, and mixed methods. (Please see details below under “Additional Instructions for Submitting an Alaskan Regional Outlook").

• Additional Outlook report details, including discussions and details related to uncertainties/probabilities. (Uncertainty values are solicited for the pan-Arctic only).

• Executive summaries describing in plain words your Outlook, contributing factors, and your methodology.

• Contributors who do not have access to the Google Form or a Google account should send their submission materials and a PDF of the submission form via email to seaiceoutlook@gmail.com.
  
  

Additional Instructions for Submitting an Alaskan Regional Outlook

• Please submit a total extent for the Alaskan region, defined here as the combination of the Bering, Chukchi, and Beaufort seas. If possible, use the definition from the NSIDC Arctic sea ice regional graphs and time series from the mask below, which is on the 25 km by 25 km polar stereographic projection used for the passive microwave satellite data.

• The mask is provided as a NetCDF file here: NSIDC Regional Mask (NC - 2 MB).

• Also tell us the maximum possible ice extent if every ocean cell in your Alaska region were ice covered. For example, if your model uses exactly the same grid as the satellite data, the area would be 4.00 x 10^6 km^2. The maximum possible extent is probably much larger than your actual Alaskan Regional Outlook. Be sure to exclude land and islands.

• Finally, with your entry, please include how you defined the Alaskan region: either say NSIDC definition, or if you must use your own definition, describe it.

• Enter your submission via the Google-based submission form under the "Outlook Prediction" header.

• For questions about the format of this request, please contact the SIO team (seaiceoutlook@gmail.com).

Note: If you skip this step but provide full fields, we'll compute an Alaskan regional outlook for you.

Instructions for Submitting Full Field of Sea Ice Forecasts

• To contribute fields of SIP, IFD, IAD (or the daily sea ice concentration fields, from which we will calculate the SIP, IFD and IAD for you) and initial conditions, please upload to the SIPN data server using the same username and password of past years. If you are a new contributor of these fields and need to set up a new username and password, or have any queries on how to upload the data, please contact Ed Blanchard at edwardbw@uw.edu.

• For examples and further information on the SIP, IFD, and IAD metrics, see Metrics for the Sea Ice Outlook.

Instructions for Submitting Pan-Arctic Sea Ice Extent Anomalies (optional)

This is an optional submission and it is recognized that not all SIO contributors will be able to provide anomaly forecasts. The request is motivated by the large spread in SIO predictions of mean September sea-ice extent. Some of this spread likely reflects inter-model biases, i.e., some models consistently overestimate ice extent while others underestimate it (relative to observations). The goal of this activity is to eliminate this source of inter-model prediction spread. The long-term mean is not a well-defined concept in a rapidly changing Arctic.

The pan-Arctic sea ice extent anomaly is the departure of the contributors' September extent Outlook relative to the contributors' baseline trend, e.g., the trend in historical observations, model hindcasts, etc.

To calculate a pan-Arctic sea ice extent anomaly:

1. Calculate the multi-year linear trend (slope) of September-mean extent from your baseline period. The linear trend will be different for each contributor due to inter-method/model biases.

2. Extrapolate the linear trend to calculate an extrapolated September 2026 extent value.

3. Calculate the extent anomaly value by subtracting the September 2026 Outlook extent from the extrapolated trend September 2026 value.

Instructions for Submitting Supplemental Material (optional)

• Send supplemental material as an e-mail attachment sent to seaiceoutlook@gmail.com.

• Please provide supplemental material as a single PDF (less than 20 MB).

• Clearly identify your contribution by using the same email address and group name as provided on the submission form so we can link it to your submission.

• Examples of supplement materials include: relevant figures, imagery, references, or further information about your methods.

REMAINING 2026 SIO SCHEDULE

JULY: (Based on May and June data)
- 13 July 2026 (Monday): Deadline for July Contributions

AUGUST: (Based on May, June, and July data)
- 13 August 2026 (Thursday): Deadline for August Contributions

SEPTEMBER: (Based on May, June, July, and August data)
- 14 September 2026 (Monday): Deadline for September Contributions

POST-SEASON REPORT
- Focus will be on the performance of Outlooks as compared to sea-ice minimum.
- Additional discussion and analysis of factors driving sea-ice extent during the 2026 melt season
- Developed following the conclusion of the retreat season.