NYC July 21 High Temp: Will 80-81°F Win the Market?

New York City’s highest temperature on July 21 is already happening as this market resolves at noon. The 80-81°F range sits at 41.5% implied probability, making it the leading outcome in a crowded field of eleven brackets. That lead is narrow. The 78-79°F and 82-83°F brackets are close enough to matter, and a one-degree forecast error is all it takes to shift payouts entirely.

The market question asks whether NYC’s official high reading on July 21 lands between 80 and 81°F. The YES price is $0.42 and the NO price is $0.59. Resolution closes at noon on July 21, 2026. Total trading volume is $61,170, with $58,794 of that arriving in the last 24 hours, a sign that traders moved hard into this market overnight.

How the 80-81°F Contract Works

YES pays out if NYC’s highest temperature on July 21 falls exactly within the 80-81°F band. NO pays out if the official high lands anywhere else, including one degree lower or one degree higher. The resolution source is Polymarket’s market resolution process, which uses official weather station data for New York City.

• YES ($0.42, 41.5% probability): NYC official high reads 80°F or 81°F on July 21.
• NO ($0.59, 58.5% probability): NYC high lands below 80°F, above 81°F, or at any other bracket value.

The NO side wins whenever the temperature misses this two-degree window. That window is narrow by design. With ten other brackets splitting the remaining probability, each adjacent band pulls meaningful share. The 78-79°F and 82-83°F bands are the primary threats to YES, not the extreme outcomes.

Momentum and Market Signals

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The momentum picture is mixed but leans toward stabilization. The 24-hour price change is up 2.5%, with no movement in the last hour, and a trend score of 43.51 suggests the market is not strongly committed in either direction. The overnight volume surge from $0 to $58,794 in 24 hours tells the real story: traders priced this aggressively as July 21 weather data came into view, then held position near the open.

Total volume of $61,170 with $78,887 in liquidity is thin. This is well below the $1 million threshold where price stability becomes reliable. A single large position in any adjacent bracket could move the 80-81°F price by several cents. The market is pricing real meteorological uncertainty, not a settled forecast.

• The 24-hour price gain of 2.5% and flat 1-hour movement together signal the market found a short-term equilibrium overnight as forecast data firmed up.
• Volume spiked from near zero to $58,794 in 24 hours, meaning almost all price discovery happened in a single trading session.
• Liquidity of $78,887 is adequate for small positions but thin enough that new weather data could reprice this contract sharply before noon resolution.
• The trend score of 43.51 sits below the neutral midpoint, consistent with a market that leans toward NO but has not broken away from YES.
• Trader sentiment reads 41.5% YES and 58.5% NO, a modest bearish lean rather than strong conviction on either side.

Lines Analysis: What the Data Says About NYC’s July 21 High

The 80-81°F range is climatologically reasonable for a New York City July day. Late July highs in Manhattan cluster in the upper 70s to mid-80s under typical conditions. A surface high sitting over the region tends to push afternoon temperatures toward 80-84°F, while sea breeze penetration from the Atlantic can cap temperatures in the low 80s. If the forecast models are aligned on a high near 81°F, this bracket captures a real slice of probability.

The adjacent brackets create the genuine NO risk. The 82-83°F band wins if the city runs a degree or two warmer than the central forecast. The 78-79°F band wins if marine influence or cloud cover holds temperatures down. At resolution time of noon, the official high may not even be set yet depending on the measurement methodology, which adds a timing dimension specific to this contract’s structure.

• National Weather Service New York forecast updates before noon on July 21 would be the single most important signal for repricing.
• Any observed temperature reading at Central Park or JFK above 82°F before noon shifts probability sharply toward the 82-83°F bracket.
• A cooler-than-forecast morning high or persistent cloud cover would benefit the 78-79°F bracket over 80-81°F.
• Humidity and dew point readings this morning give indirect evidence of how high the dry-bulb temperature can climb before noon.
• The noon resolution cutoff means this contract resolves before the typical peak heating hour of 2-4 PM, which may structurally suppress the measured high relative to a full-day observation.

Total volume of $61,170 is thin. The data as of this writing favors 80-81°F as the modal outcome, but the 58.5% NO probability correctly reflects how much probability mass sits in adjacent brackets. Here’s what the measurements are telling us: this is a competitive spread market, not a binary call on whether it gets hot.

LINES VERDICT

NARROW LEAD, HIGH UNCERTAINTY

The 80-81°F bracket is the most likely single outcome, but with eleven brackets splitting probability, NO is the statistically favored position simply by covering the other ten.

What the market says: At 41.5% implied probability, the market treats 80-81°F as the modal pick in a fragmented field. Thin volume below $100,000 means price can shift quickly on any observed temperature reading before the noon cutoff.

Key unknown: The actual observed temperature at NYC’s official measurement station before noon on July 21 is the only data point that matters. Any reading above 81.5°F or below 79.5°F collapses this contract to near zero before resolution.