The Interim Post-Season Report for 2018 Sea Ice Outlook (SIO) is now available online. The goal of the SIO is to improve sea ice prediction on seasonal time-scales. This interim report is intended as a quick post-season update that summarizes how the outlooks did in comparison to the observed minimum extent. The September monthly averaged sea ice extent was 4.71 million square kilometers, based on the National Snow and Ice Data Center (NSIDC) Sea Ice Index. The median extent of the 39 Outlook contributions for June, July, and August were 4.60, 4.70, and 4.57 million square kilometers, respectively. A full post-season report in January 2019 will include an in-depth analysis of factors impacting sea ice this season; further discussion about the outlooks; comments on regional observations, predicted spatial fields, Antarctic contributions; and a summary from the Sea Ice Drift Forecast Experiment. This report is the product of the Sea Ice Prediction Network–Phase 2 (SIPN2) effort.