Buenos Aires on May 18 enters the Southern Hemisphere's late autumn, when typical high temperatures range between 10 and 20 degrees Celsius. The current prediction market prices YES—meaning the day's high stays at 10°C or below—at just 1%, a clear signal that traders expect the city to avoid unusually cold conditions. This extremely low odds reflects the rarity of such chilly days in mid-May, as Buenos Aires typically benefits from residual warmth before winter truly sets in. The resolution criterion is straightforward and verifiable through official weather data recorded by Argentina's meteorological service. The massive gap between 1% and a fair 50-50 odds level indicates strong trader confidence that May 18 will bring typical autumn temperatures or warmer. This market captures bets on the boundary between mild and cold: at exactly 10°C, the outcome hinges on decimal precision and official measurement rounding. Historically, May temperatures in Buenos Aires rarely dip below 8-9°C except during unexpected cold fronts, making such an event a meaningful but unlikely catalyst for the YES outcome.
What factors could move this market?
Buenos Aires occupies a humid subtropical climate zone with significant seasonal variation, but May typically represents a gentler transition from autumn's mildness into winter's sharper cold. The city's location at approximately 34.6 degrees south latitude, combined with its proximity to the Río de la Plata estuary, moderates extreme temperature swings year-round. Historical weather data for May shows average highs clustering around 16–18°C, with lows typically between 10–13°C; a day where the high fails to exceed 10°C requires an anomalous weather pattern—either an unseasonable cold front pushing up from Patagonia or a particularly weak high-pressure system allowing Antarctic air to penetrate northward. Such events occur perhaps once or twice per May across a decade-long span, explaining the 1% odds traders have assigned.
The factors favoring a YES outcome hinge on specific meteorological conditions: a strong southwesterly wind surge, a deep low-pressure trough, or a collision between warm Atlantic air masses and frigid southern air masses could all suppress daytime highs. Cold fronts in May are not unknown; Argentina's meteorological service tracks them regularly, and historical records document occasional Mays where early-winter-like conditions arrive ahead of schedule. Additionally, the definition of high temperature depends entirely on official measurements from the Argentine weather station—if May 18 is a particularly overcast day with persistent cloud cover or rainfall, solar heating would be limited, and afternoon maximums could compress downward.
Conversely, the overwhelming 99% of traders betting against YES expect typical May conditions to dominate: persistent high-pressure systems, abundant sunshine from late autumn's still-reliable daylight hours, and the residual thermal inertia of the ocean and estuary keeping microclimates mild. Buenos Aires' urban heat island effect—generated by asphalt, buildings, and reduced vegetation—typically adds 2–3°C to official station readings in downtown areas, though the meteorological station may be located in a more suburban or exposed site. The current date context matters: mid-May is well before the coldest months (July–August), meaning traders are implicitly betting that no extreme catalysts will emerge. Weather forecast models extending 1–2 weeks out rarely show May 18 as exceptional, and the absence of any forecast anomaly supports the low YES odds.
The 1% price also encodes trader confidence in the resolution mechanism itself—the official weather service's historical accuracy and standardized measurement protocols. This is a cleanly resolvable bet: on May 19, the highest temperature recorded on May 18 will be either at-or-below 10°C (YES) or above 10°C (NO).
What are traders watching for?
Monitor Buenos Aires meteorological service forecasts May 15–18; any strong cold-front alert would shift YES probability substantially upward.
Watch South Atlantic pressure patterns May 10–17; sustained low-pressure trough favors colder air advection northward into Argentina.
Cloud cover and rainfall on May 18 reduce solar input; persistent overcast conditions compress afternoon temperature highs downward.
Official May 18 daily maximum from Argentina's meteorological service resolves market; station microclimate and measurement protocol matter.
How does this market resolve?
The market resolves on May 19 based on the official maximum temperature recorded by Argentina's meteorological service for May 18, 2026. YES wins if the high temperature is 10°C or below; NO wins if it exceeds 10°C.
Polymarket Trade is an independent third-party interface to the Polymarket CLOB prediction market exchange on Polygon — not affiliated with Polymarket, Inc. Prediction markets aggregate trader expectations into real-time probability estimates. 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. Polymarket Trade is non-custodial — your funds never leave your wallet. Open the full interactive page linked above to place orders, see order book depth, and execute a trade.
