Dallas High Temp on May 21: Market Stuck Near a Coin Flip

The Dallas high-temperature market for May 21 is sitting at nearly dead even. The 75°F or below outcome carries a 47.5% probability right now, with the NO side holding a slim edge at 52.5%. That gap is razor-thin. When a weather market splits like this, the market is pricing uncertainty, not science.

What makes this market genuinely interesting is the one-hour price swing. The 75°F or below outcome dropped 32.5% in a single hour on May 20, 2026, a sharp reversal that signals fresh forecast data hit the market and traders repositioned fast. The trend score of 80.57 says momentum is leaning against this outcome right now. Whether that holds through May 21 resolution depends entirely on what North Texas weather systems do in the next 24 hours.

How the Dallas Temperature Contract Works

This contract resolves based on the official highest temperature recorded in Dallas on May 21, 2026. YES pays out if the Dallas high on that date reaches 75°F or below. NO pays out if the high comes in at 76°F or above, across any of the alternative brackets spanning all the way up to 94°F or higher. Resolution is scheduled for 2026-05-21 12:00:00.

• YES (75°F or below): Price 0.48, implied probability 47.5%
• NO (76°F or higher, any bracket): Price 0.53, implied probability 52.5%

The NO side covers a wide range of outcomes. Any temperature from 76°F through 94°F-plus clears the bar. For YES to miss, the Dallas high on May 21 simply needs to crack 76°F, which is historically well within normal late-May range for North Texas. The National Weather Service climatological average high for Dallas in late May sits in the low-to-mid 80s. A reading of 75°F or below on May 21 would represent a notably cool day for the season.

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Momentum and Market Signals Heading Into Resolution

The combined momentum signal here is tilted against YES. The 32.5% one-hour drop, a trend score of 80.57, and thin market volume all point in the same direction: traders who looked at updated forecast data moved away from the cool-day outcome. What likely drove that repositioning was a weather model update showing warmer air holding over the Dallas-Fort Worth metro area through May 21.

Volume tells a different story about conviction. Total market volume is $3,974, with $3,929 of that trading in the last 24 hours. Liquidity sits at $12,177. This is a thin market. When total volume runs under $1M, a single moderate-size trade can move price sharply. The spread between 0.48 and 0.53 could widen or close fast if a large position hits the order book before resolution.

• The one-hour price drop of 32.5% on YES is the dominant signal. It points to a weather model shift showing warmer conditions over Dallas on May 21.
• A 24h volume of $3,929 against total volume of $3,974 means nearly all activity concentrated in the last day. This is a late-mover market.
• The trend score of 80.57 confirms directional pressure against the cool-day outcome, consistent with a warming forecast signal.
• Liquidity of $12,177 in an under-$5K volume market means the order book is relatively deep for the size. Price movement on a new trade could still be significant.
• The 52.5% NO lean is narrow. Any overnight forecast revision showing a cold front or cloud cover could flip this market before 2026-05-21 12:00:00.

Lines Analysis: What Dallas Climatology and Forecast Data Say

Late May in Dallas skews warm. The National Weather Service historical record shows Dallas averages highs in the 82-86°F range during the third week of May. A reading at or below 75°F would require an unusual cold air intrusion or sustained overcast conditions suppressing daytime heating. The climatological baseline alone makes YES a below-average probability proposition, independent of whatever the current short-range forecast shows.

What keeps YES alive at 47.5% is the specific dynamics of this year’s late-May weather pattern across the Southern Plains. Elevated moisture and cloud cover tied to active storm systems can hold Dallas highs well below seasonal norms. If convective cloud cover persists through May 21 morning, daytime heating gets capped early. That scenario is not implausible. The National Weather Service Storm Prediction Center has flagged active severe weather setups across North Texas in this period, which typically come with cloud cover that suppresses afternoon highs.

Signals to monitor before 2026-05-21 12:00:00 resolution:

• National Weather Service Fort Worth forecast updates overnight May 20-21 will set the final market signal. Any revision below 76°F pushes YES above 50%.
• Morning cloud cover and precipitation reports from Dallas-Fort Worth International Airport will be the ground-truth indicator before the market resolves.
• Storm Prediction Center mesoscale discussion bulletins overnight could confirm or deny the cloud-cover suppression scenario that keeps YES viable.
• Any 00z or 06z model run showing a front stalling near Dallas overnight sharply increases the probability of a sub-76°F high.

With volume at $3,974, this market reflects a small group of traders making targeted weather bets, not broad consensus. The data currently favors NO given late-May climatology and the recent forecast shift that drove the one-hour drop. But the spread is narrow enough that one good forecast update could reprice the whole contract before the 2026-05-21 12:00:00 close.

LINES VERDICT

Lean Warmer: NO Side Has the Climatological Edge

Late-May Dallas climatology and the sharp one-hour momentum drop both point away from the cool-day outcome. The data doesn’t care about the politics of forecast uncertainty.

What the market says: 47.5% probability for 75°F or below. The near-even split reflects genuine forecast uncertainty heading into a 24-hour resolution window. Thin volume means this price can move fast on any overnight model update before 2026-05-21 12:00:00.

Key unknown: The National Weather Service Fort Worth overnight forecast update is the single data point that will reprice this contract. A forecast high of 75°F or below flips the market; anything above 76°F confirms the current NO lean.

Scientific Context: Dallas in Late May

Dallas-Fort Worth sits in a region where late-May temperatures are governed by the interplay of Gulf moisture, Great Plains convective systems, and periodic cold frontal passages from the north. The climatological high for May 21 in Dallas runs between 82°F and 86°F in most recent decades, based on NOAA historical station data for DFW International Airport. Readings at or below 75°F on this date occur in roughly 10-15% of years, making the current 47.5% probability a meaningful overvaluation relative to base rates unless short-range forecast data strongly supports a cool outcome.

Active storm seasons, like the current 2026 pattern across the Southern Plains, can compress that base-rate gap by bringing cloud cover, rain-cooled air masses, and persistent overcast conditions that suppress afternoon heating. The market is attempting to price exactly this conditional probability. Here’s what the measurements are telling us: without confirmed cloud cover or precipitation in the May 21 morning hours, the base rate argues against YES.

Frequently Asked Questions

• What does 47.5% probability mean here? The market assigns roughly a coin-flip chance that Dallas records a high of 75°F or below on May 21, 2026. It reflects split trader opinion, not settled forecast science.
• What pays out on NO? Any Dallas high temperature of 76°F or above on May 21, 2026, across any bracket from 76-77°F all the way to 94°F or higher, resolves the NO side as correct.
• What data would move this price before resolution? A National Weather Service Fort Worth forecast update showing a high below 76°F would push YES above 50%. A warm forecast confirmation pushes NO further ahead.
• When does this contract resolve? Resolution is set for 2026-05-21 12:00:00. Official temperature data from the Dallas-Fort Worth area determines the outcome.
• Is the volume reliable for reading price signals? Total volume is under $5,000, which is very thin. Price can move sharply on a single moderate trade. Treat the 47.5% probability as directional, not precise.

This analysis reflects market conditions as of 2026-05-20 05:10:25. Prediction market probabilities are volatile and shift as new data and regulatory decisions emerge, especially as the 2026-05-21 12:00:00 resolution date approaches. Lines.com does not accept bets or provide financial or gambling advice. All market outcomes are uncertain.