San Francisco's climate in May typically features highs ranging from the mid-60s to low-70s Fahrenheit, making precise single-degree forecasts particularly challenging. This market asks whether the city's maximum temperature will fall within the narrow 62-63°F range on May 19, 2026. The 2% YES odds reflect trader skepticism about this specific outcome, suggesting strong consensus that the high will fall either below 62°F or above 63°F. At just 2% implied probability, the market reveals confidence in broader temperature outcomes being far more likely than this narrow band. Resolution depends on the official high temperature recorded for San Francisco on May 19, typically sourced from NOAA or local weather authorities. Such precise temperature ranges illustrate how prediction markets quantify extremely specific meteorological forecasts that ordinary weather forecasts rarely venture into.
Deep dive — what moves this market
San Francisco's weather is driven by complex interactions between marine air from the Pacific, the California Current's cool waters, and local topographic features. May represents a transitional month in the Bay Area, where sea surface temperatures begin warming but marine layers still frequently develop. Historically, May highs in San Francisco average around 69-70°F, though daily variation is significant. A high of 62-63°F would represent a notably cool day, roughly 6-8 degrees below the monthly average. Such cooler conditions typically emerge during persistent marine layer events, coastal upwelling, or atmospheric systems bringing cooler air masses southward. The 2% odds suggest traders have assigned minimal probability to this narrow range despite its physical plausibility. Several factors could push toward YES: an unusually strong marine layer on May 19 could suppress temperatures throughout the day; a low-pressure system or coastal trough could drive cooler air into the region; persistent cloud cover and westerly winds would enhance cooling effects. Historically, May has seen daily highs as low as the high 50s, so 62-63°F is meteorologically achievable. Conversely, most outcomes favor NO. Warming from spring solar forcing typically accelerates in May. High-pressure systems, which bring clear skies and warmth, grow increasingly common. Land heating during daylight tends to overcome marine influences by late spring. Traders betting NO likely expect either genuinely warm conditions (low-to-mid 70s) or mild conditions (65-69°F), both far more statistically common in May than this cool band. The extremely low 2% odds reflect not just the statistical rarity of any single 1-degree window, but also trader confidence in broader seasonal patterns. The spread between this outcome and warmer alternatives reveals strong conviction that May weather will trend toward typical or above-typical warmth. Prediction markets on weather typically show highest concentration around probabilistically central outcomes. The fact that this narrow cool band sits at the extreme left tail explains both its low odds and relatively modest liquidity.
What traders watch for
Official NOAA/NWS high temperature recording for San Francisco on May 19: the definitive resolution metric.
Marine layer development and coastal fog persistence on May 19: strong marine influence supports cooler outcomes.
High-pressure system positioning and clearing patterns: major sunshine favors highs above 65°F.
Spring solar heating acceleration: late May warming trends typically dominate cool coastal air masses.
How does this market resolve?
This market resolves based on the official high temperature recorded for San Francisco on May 19, 2026, from NOAA or equivalent authoritative weather source. YES if the high falls between 62–63°F inclusive; NO otherwise.
Prediction markets aggregate trader expectations into real-time probability estimates. On Polymarket Trade, every market question resolves YES or NO based on a specific event outcome; traders buy shares of the side they believe will resolve positively. Prices range 0¢ (certain no) to 100¢ (certain yes) and naturally reflect the crowd-implied probability of YES. This page summarizes the market state for readers arriving from search; for live trading (place orders, see order book depth, execute a trade) open the full interactive page linked above.
