San Francisco Hit 66-67°F on July 9, 2026 | Lines.com

San Francisco recorded a daily high of 66 to 67 degrees Fahrenheit on July 9, 2026, as measured at San Francisco International Airport Station. The 66-67°F bracket resolved YES on Polymarket, confirming a reading slightly below the city’s historical July average of roughly 68 to 70°F. Traders who held the 66-67°F outcome through resolution were paid out at full value.

The market opened at 33% implied probability, meaning early traders gave this bracket less than a one-in-three chance of winning. By close, the price had reached 99.5%, a 66-percentage-point swing driven almost entirely by the final 24 hours of trading. That late surge reflects real-time temperature data filtering into the market as the day progressed. The $42,553 total volume, with $32,859 arriving in the final 24 hours, signals that traders moved decisively once the measurement came into focus.

San Francisco Recorded 66-67°F on July 9

The official high came from the San Francisco International Airport Station, the designated resolution source for this Polymarket contract. The 66-67°F reading placed the city’s peak temperature below the historical July daily average, consistent with San Francisco’s marine-layer-influenced summers. July highs at SFO frequently stay in the mid-60s to low 70s depending on fog patterns and onshore flow strength. A 66 to 67°F ceiling is a normal outcome, not an outlier.

The market’s final hours told the real story. The 24-hour price change of plus 58.5 percentage points is a near-textbook pattern for a temperature market resolving on live observational data. As readings at SFO tracked toward 66-67°F through the day, traders reallocated from competing brackets to this one. By the time the market closed at noon Pacific on July 9, the price had converged at 99.5%.

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How the Market Priced a 66-67°F Day

At market open, the 66-67°F bracket carried a 33% implied probability. That opening price correctly flagged the outcome as possible but not dominant. Eleven possible brackets competed for volume, and spread across those options, 33% for any single two-degree window is reasonable. What the early market underweighted was the probability of a marine-influenced, below-average-high day. The data doesn’t care about the politics of what traders expected. SFO measured what it measured.

The $42,553 in total volume is modest by multi-event Polymarket standards but meaningful for a single-day temperature bracket. The $118,512 in liquidity provided solid price discovery quality. The fact that 77% of total volume arrived in the final 24 hours confirms this was a market that settled on conviction late rather than early. Here’s what the measurements are telling us: the market was underpriced at open and accurately priced by close.

MARKET PERFORMANCE SUMMARY

• Resolution Outcome: 66-67°F bracket confirmed YES at San Francisco International Airport Station on July 9, 2026.
• Article-Time Probability: 33% at market open.
• Final Price at Close: 99.5% (1.00).
• Total Volume: $42,553 (77% arriving in the final 24 hours).
• Market Assessment: Underpriced YES at open. Correctly priced by close as real-time temperature data resolved uncertainty.

What a 66-67°F Resolution Means for Weather Market Structure

San Francisco’s July temperature profile is driven by cold Pacific upwelling and morning fog patterns. A 66-67°F high on July 9 sits at the cooler end of normal. AccuWeather’s July 2026 forecast for San Francisco placed daily highs in the 59 to 71°F range, meaning the resolved outcome fell squarely within the expected distribution. The market is pricing uncertainty, not science. When the science is this well-characterized, markets tend to converge accurately given enough time.

The binary-style resolution structure worked well here. Eleven two-degree brackets effectively sliced a roughly 19-degree expected range into equal probability cells. Early in the market’s life, volume spread across the most likely central brackets. As observational data tightened the range on July 9, volume concentrated into the correct bracket rapidly. That convergence pattern suggests the market design and the measurement source were well-matched for this event type.

FORWARD SIGNALS

• San Francisco International Airport Station remains the designated resolution source for all SFO-based temperature markets on Polymarket. Future July markets should anchor their prior probability distributions in the 64 to 72°F range given historical averages and marine-layer variability.
• Markets that open with volume spread across many brackets tend to see late-day volume concentration as observational data resolves uncertainty. Traders who enter these markets early accept higher uncertainty risk in exchange for better opening prices.
• The 33% opening price on the eventual winner reflects the legitimate difficulty of picking a single two-degree bracket from eleven options. That opening price was not mispriced. It became underpriced only in retrospect as the actual measurement narrowed the field.
• San Francisco’s fog-driven summer climate makes consecutive warm-day streaks less likely than comparable inland California cities. That suppresses probability for the upper brackets (74°F and above) and concentrates expected outcomes in the 64 to 70°F zone.

LINES RESOLUTION VERDICT

RESOLVED YES: 66-67°F CONFIRMED

The market correctly landed on the right outcome by close, but traders who entered at 33% captured the real value in this contract. The marine-layer climate at SFO was always likely to keep the July 9 high in the mid-60s, and the late-day volume surge confirmed what the temperature record showed.

What the market showed: The 66-67°F bracket opened at 33% implied probability and closed at 99.5% after real-time observational data resolved the outcome. The market moved from genuinely uncertain to nearly certain within 24 hours, driven by $32,859 in late-session volume out of $42,553 total. The opening price was reasonable given eleven competing brackets. The closing price was accurate.