Trade: Highest temperature in Seattle on May 11?

Market context

On 11 May 2026, the highest temperature recorded at Seattle-Tacoma International Airport will fall within one of several defined ranges. The settlement will draw from historical weather data logged at KSEA, the primary observation station for the Seattle metropolitan area, with resolution occurring once Wunderground finalises the day's records. The current order book on Polymarket shows 0% implied probability across all temperature brackets, indicating either minimal trading activity or a technical issue with market initialisation rather than genuine consensus that no temperature will be recorded.

Seattle's May climate typically produces highs between 65–75°F (18–24°C), with occasional warm spells pushing toward 80°F (27°C). Historical May records at KSEA show a maximum of 89°F (32°C) set in 1960, though readings above 85°F occur roughly once per decade in this month. The current flat probability distribution suggests traders have not yet engaged with range-specific outcomes, making this an early-stage market where baseline seasonal patterns and any emerging weather forecasts will shape positioning as May 2026 approaches.

Traders monitoring this market should track Pacific Northwest weather patterns from late April onwards, particularly ridge-building high-pressure systems that can drive unseasonable warmth into the region. The National Weather Service's extended forecasts, typically issued 8–14 days prior, will provide the first concrete signals of anomalous conditions. El Niño or La Niña phase strength in early 2026 may influence seasonal temperature tendencies, though such signals remain distant from current forecasting horizons.

Resolution source

This market settles from the official outcome published at https://www.wunderground.com/history/daily/us/wa/seatac/KSEA. A proposer submits the final result to the UMA optimistic oracle on Polygon; the two-hour dispute window closes and payouts clear in USDC.

How to trade this market step by step

The mechanics for trading "Highest temperature in Seattle on May 11?" are the same as any other PolyGram event contract. Each YES share resolves to $1 if the event happens, or $0 if it doesn't. The current price between 0¢ and 100¢ is the market's probability estimate, set live by the order book.

1. Sign in on polygram.ink with your email — no full KYC under $1,500 lifetime trading volume.
2. Deposit USDC on Polygon (lowest fees, ~$0.01 per transaction) or Ethereum. Funds credit after 12 confirmations.
3. Pick a side. Buy YES if you believe the event will happen; buy NO if you think it won't. The current YES price reflects the market's collective probability.
4. Size your position. If you stake 100 USDC at 50% YES, you'll receive shares that pay $200 if YES resolves true — a 100% gross return. If NO resolves, your shares are worth $0.
5. Set risk controls (optional). Stop-loss, take-profit, and limit-order types all supported. Use the trade ticket's slippage box to cap your maximum entry price.
6. Wait for resolution. When the event resolves on-chain via the UMA optimistic oracle, the winning side settles to 100¢ automatically and USDC hits your balance within seconds. Withdrawable to any wallet you control.

How active is this market?

$29K in lifetime turnover and $12K of resting liquidity puts this market in the around the median by volume for weather contracts on PolyGram. Order-book depth is modest — expect a couple of cents of slippage on $1k+ trades.

Last 24 hours alone saw $19K in turnover, well above the lifetime daily-average for this market — a clear sign of news catalysing trader activity right now.

The market has been open for under a month — fresh enough that information asymmetry remains a real factor.

Higher-volume markets tend to have tighter spreads and faster price discovery — meaning the displayed YES/NO percentages are more likely to reflect the true crowd-implied probability rather than a single trader's directional view.

Key terms

YES / NO share

A binary outcome token that pays $1.00 if the underlying claim resolves true (YES) or false (NO), and $0 otherwise. The market price between 0¢ and 100¢ is the implied probability.

CLOB

Central limit order book. The matching engine that pairs YES buyers with NO buyers (effectively the same trade). Polymarket's CLOB on Polygon executes trades on-chain via the conditional-tokens framework.

Liquidity

USDC capital sitting in resting limit orders inside the order book. Deeper liquidity means smaller slippage on large trades and a tighter bid-ask spread.

UMA optimistic oracle

The on-chain dispute system that settles each Polymarket market. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution.

Slippage

The difference between the displayed mid-price and your fill price. Affects market orders most; limit orders avoid slippage but may take time to fill.

Conditional token

ERC-1155 outcome share issued by Gnosis Conditional Tokens on Polygon. The token type that resolves to $1.00 or $0.00 at settlement.

See the full prediction-market glossary →

Frequently asked questions

Risk and regulatory note

Prediction-market positions can lose 100% of staked capital. Outcomes are uncertain by definition — historical accuracy of crowd-implied probabilities is high in aggregate but not for any single market. PolyGram does not provide investment advice. Trade only with capital you can afford to lose.

Regulatory status varies by jurisdiction. Germany, the United States, and most EU countries treat Polymarket-style event contracts under one of three frameworks: financial derivative, gambling product, or unregulated novel asset. Consult local counsel before trading.

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