The summer circulation pattern was quite unsettled over the Arctic Ocean, with persistently below-normal sea-level pressure, especially to the north of Siberia. The Arctic Oscillation was generally positive, corresponding to lower than normal pressure in the high latitudes. Here are monthly maps of sea-level pressure anomaly from June through August.
Based on the 19 Arctic coastal observing sites that I've used before on this blog (e.g. here), temperatures were quite close to the 1981-2010 normal this summer on average around the Arctic basin, and this is a marked contrast from the persistent and extreme warmth of 2016. The first chart below shows this year's June-August mean temperature in the context of recent decades, and the second chart shows the rather sudden cooling (relative to normal) that has occurred since late winter.
Given that Arctic sea ice extent is still far below normal, it's very likely that unusual warmth will return around the Arctic basin this autumn as the wide expanse of open water provides a direct heating influence; this post from last year shows the extraordinary warming trend for the month of October. It will be interesting to see how the winter turns out, but in light of recent years it would be surprising to see anything other than significantly above-normal temperatures again for the seasonal mean over the Arctic basin.