Resolution criteria on PolyGram: This market will resolve according to the total precipitation in mm at Heathrow (London Airport) in May, 2026, according to the Met Office. If the reported value falls exactly between two brackets, then this market will resolve to the higher range bracket. The resolution source for this market will be the Met Office, specifically the figure for May 2026 under "rain mm" at the https://www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/heathrowdata.txt link once the Provisional figure for the whole month of May 2026 is released. If the relevant data is not available by July 7, 2026, 11:59 PM ET, another credible resolution source will be chosen.
PolyGram is an on-chain prediction market where you trade YES or NO outcome shares with real USDC on Polygon. For this market, buy YES if you believe the event will happen, or NO if you think it won't. Your maximum loss is your stake — winning shares pay $1.00 each at resolution. Unlike sportsbooks, there is no house edge: prices are set by supply and demand from other traders and reflect the crowd's real-time probability.
Market outcomes
| <5mm | 5% YES | 95% NO |
| 5-10mm | 16% YES | 84% NO |
| 10-15mm | 41% YES | 59% NO |
| 15-20mm | 24% YES | 76% NO |
| 20-25mm | 24% YES | 76% NO |
| 25-30mm | 24% YES | 77% NO |
| 30mm+ | 33% YES | 67% NO |
This market concerns whether London will receive measurable precipitation during May 2026, with settlement determined by Met Office data from Heathrow Airport. The current order book implies a 2% probability of any rainfall occurring across the entire month, suggesting traders expect May 2026 to be exceptionally dry.
Historical precipitation records at Heathrow show May typically receives between 40–50 mm of rainfall, with the month rarely experiencing zero precipitation. Since 1953, May has produced measurable rain in the vast majority of years; completely dry Mays are extraordinarily rare events. The current 2% implied probability reflects this statistical rarity, pricing in only the most extreme drought scenarios. For context, May 2020 saw 16.2 mm and May 2019 recorded 26.4 mm at Heathrow, both well above the threshold this market requires.
Traders should monitor seasonal weather forecasts released by the Met Office in April 2026, which typically provide 30-day outlooks indicating precipitation likelihood. The North Atlantic Oscillation and broader Atlantic circulation patterns, observable through winter and early spring 2026, will influence May rainfall prospects. Any significant drought declarations or water authority warnings issued in spring 2026 could shift market sentiment. The final settlement depends on the Met Office's provisional May 2026 rainfall figure, due by early June, with resolution confirmed by 7 July 2026.
Resolution is handled by the UMA optimistic oracle on Polygon. A proposer submits the outcome, a two-hour dispute window opens, and if no one stakes a counter-claim the payout is final. Contested outcomes escalate to UMA token-holder voting. Payouts clear in USDC to the winning side.
The mechanics for trading "Precipitation in London in May?" 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.
$2K in lifetime turnover and $388 of resting liquidity puts this market in the below the median by volume for weather contracts on PolyGram. Order-book depth is thin — large orders may need to be split across the book or executed as limit orders.
Last 24 hours alone saw $93 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.
Resolution is handled by the UMA optimistic oracle on Polygon. A proposer submits the outcome, a 2-hour dispute window opens, and if uncontested the payout is final. Contested outcomes escalate to UMA token holders.
This prediction market is scheduled to close on 31 May 2026. After the resolving event occurs, settlement typically clears within 24 hours once the UMA optimistic oracle confirms the outcome. All payouts are in USDC on the Polygon network.
To trade on this prediction market, create a free PolyGram account at polygram.ink, deposit USDC via Polygon, and place a YES or NO order on the outcome you believe in. You can learn more on our how-it-works page. Your maximum loss is limited to your stake — there is no leverage or margin.
When the outcome is determined, winning YES shares pay out $1.00 each in USDC, while losing shares pay $0. Settlement is handled by the UMA optimistic oracle on Polygon — a proposer submits the result, a two-hour dispute window opens, and if uncontested, payouts are distributed automatically. You can withdraw your winnings to any Polygon wallet.
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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