Seattle weather markets track precise daily temperature ranges with granular precision. This market asks whether the highest temperature on May 18, 2026 lands in the narrow 56–57°F band—a tight range that represents cool but plausible spring weather in the Pacific Northwest. Currently trading at 0% YES odds, this market reflects strong trader skepticism that the high will land exactly in this range. Instead, market participants appear to be pricing in a scenario where temperatures fall significantly outside this band, either warming above 57°F or cooling below 56°F. Mid-May in Seattle typically sees daily highs ranging from the upper 50s to low 60s, depending on high-pressure ridges and storm systems. The extreme flatness of YES odds suggests traders have visibility into broader seasonal patterns or short-term forecasts that push them away from this specific outcome. Resolution depends entirely on the official National Weather Service high temperature recorded for Seattle-Tacoma International Airport on May 18, 2026, creating a binary outcome space.
What factors could move this market?
Seattle's late spring weather in May transitions between Pacific storm systems and warm, high-pressure ridges building from the subtropics. A daily high of 56–57°F represents cool but not unusual spring weather for the Pacific Northwest, though achieving this specific narrow band requires particular atmospheric configurations and precise timing. To reach 57°F as the daily maximum, Seattle requires sufficient daytime solar input, reduced cloud cover, and wind patterns that permit daytime warming without excessive moderation from marine boundary-layer air. High-pressure systems aloft, drier air masses, and southwesterly flow patterns typically drive higher maxima into the 60s or beyond. Conversely, below-56°F outcomes occur when low-pressure systems dominate the regional pattern, cloud cover persists throughout daylight hours, or cooler maritime air masses continue to moderate afternoon temperatures. Historical May climatology for Seattle shows considerable inter-annual variability. Some springs experience sustained warmth with multiple days in the high 60s or low 70s, while other Mays remain cool and cloudy with highs in the lower 50s. The North Pacific Oscillation phase, jet stream positioning, and timing of the spring high-pressure ridge establishment all substantially influence these outcomes. The market's stark 0% odds imply traders are extremely confident the actual May 18 high will deviate from the 56–57°F range. This likely reflects either a strong warm-weather signal visible in seasonal models—an approaching ridge system and drying pattern—or a lingering cool pattern with departing low-pressure and sustained marine air. Extended-range forecast models available a week prior typically show clear signatures of high-pressure or low-pressure dominance, which would push daily maxima well outside this narrow band, explaining the market structure. This exemplifies how granular weather range markets demand precise alignment of multiple meteorological variables to resolve YES.
What are traders watching for?
NOAA/NWS forecast update: Monitor the official Seattle daily high temperature forecast for May 18 as the event approaches
Pacific high-pressure ridge: Track whether a strong high-pressure dome establishes over the western U.S. ahead of May 18
Cloud cover and storm systems: Monitor departing low-pressure systems and any mid-level moisture limiting afternoon heating
Upper-level flow pattern: Watch jet stream positioning and trough/ridge alignment over the next week affecting May 18 weather
Climate drivers: Note whether La Niña or Madden-Julian Oscillation phase favors unusual warmth or coolness for mid-May
How does this market resolve?
Market resolves YES if the National Weather Service official high temperature for Seattle-Tacoma International Airport on May 18, 2026 is ≥56°F and ≤57°F. Resolves NO if the high is below 56°F or above 57°F.
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