Recent National Weather Service guidance and ensemble model runs show an elevated warm air mass at the 850 hPa level driving surface highs near 90 °F in Seattle on June 15, with the market’s tight clustering around the 88–91 °F bins reflecting that consensus. Positive temperature anomalies of 14–16 °C aloft, combined with downslope flow and limited marine influence, favor the upper end of seasonal norms; however, small shifts in cloud cover or wind direction could trim the peak by a degree or two. Heat advisories already in effect underscore the unusual early-June intensity, while the final NWS forecast discussion tomorrow morning will provide the last major update before resolution.