Current National Weather Service and model guidance for Seattle on August 20 points to a high near the marine-influenced low-to-mid 80s, with the 82–83 °F bin holding the highest trader-implied probability. A strengthening offshore high combined with light southerly flow is limiting marine-layer intrusion and allowing modest daytime heating, while persistent cloud cover and the moderating effect of Puget Sound cap further warming. Ensemble spreads from the GFS and ECMWF remain tight around 80–84 °F, reflecting typical late-summer variability in the Pacific Northwest rather than a strong warm or cool signal. Traders are therefore pricing the narrow range most consistent with observed sea-surface temperatures and forecast soundings, with any shift in cloud timing or wind direction the main near-term catalyst for movement.