Current National Weather Service and ensemble forecast models project a daytime high of 62–64°F for Seattle on May 18, driven by mild onshore flow and stable spring ridging with no significant cold-air advection expected. This aligns with regional climatology, where May average highs reach 65°F and sub-58°F readings occur in fewer than 5% of years at Sea-Tac. Trader consensus has priced the 58°F-or-higher outcome at 99.6% because model spreads remain narrow through the weekend, with only minor variability in cloud cover or timing of any weak front. A realistic challenge would require an unforecasted marine push or rapid overnight clearing that allows greater radiational cooling, though such shifts are rare this late in the season and would need to overcome the current 10–15°F buffer above the threshold.