Houston May 28 High: Will It Hit Ninety?

Houston’s forecast for May 28 sits at the edge of a meaningful threshold. The market puts a 54.5% probability on the high reaching 90°F or above. That’s a coin-flip with a slight lean toward heat, and with less than 48 hours to resolution, every degree matters.

The market asks: what is the highest temperature in Houston on May 28? The 90°F-or-higher outcome trades at $0.55. The field of alternatives, from 88-89°F down to 71°F or below, collectively prices at $0.46. This market resolves May 28 at noon local time against observed conditions. Total volume stands at $10,970.

How the Houston Temperature Contract Works

This contract resolves YES on the 90°F-or-higher outcome if official Houston temperature observations record a daily high at or above that threshold on May 28. All other listed bands, 88-89°F, 86-87°F, and below, represent the NO-equivalent positions against the primary outcome. The resolution source is market resolution based on observed meteorological data for Houston on that date.

• 90°F or higher: $0.55, implied probability 54.5%
• 88-89°F: part of the alternative field, collectively $0.46
• 86-87°F and below: remaining probability distributed across lower bands

The 90°F threshold fails to resolve YES when Houston’s observed high stays at 89°F or below. May late-season heat in Houston can stall short of 90°F if cloud cover, overnight moisture, or a weak frontal boundary suppresses afternoon temperatures. The National Weather Service Houston forecast is the most reliable near-term signal for whether that barrier holds.

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Momentum and Market Signals

The momentum composite, combining flat 1-hour movement, unavailable 24-hour change, and a trend score of 56.29, points to mild positive lean with no sharp conviction. The most recent visible price action on May 27 showed significant intraday swings, down 5%, up 8%, then down 10%, likely tracking forecast model updates as NWS Houston refined its May 28 temperature outlook throughout the day. That volatility compressed into today’s flat hourly read, suggesting the market found a temporary equilibrium near 54-55% as overnight model runs stabilized.

Total volume of $10,970 is thin. The $5,633 traded in the past 24 hours represents more than half the contract’s lifetime activity, which signals this market only recently attracted serious attention. Liquidity at $49,758 is healthy relative to volume, meaning a moderately sized position could still move price noticeably. At this volume level, a single new weather data point or a NWS forecast update can reprice the contract fast.

Key Factors

• The 1-hour price change sits at flat, suggesting no major new forecast data dropped in the last hour to shift conviction either direction.
• The 24-hour swing history on May 27 reflects active forecast chasing, with traders updating positions as model runs changed the probability of reaching 90°F.
• Houston’s late-May climatological average high runs near 88-90°F, placing the threshold directly at the seasonal median.
• Thin total volume below $15,000 means price can move sharply on a single NWS forecast bulletin or afternoon model update.
• The alternative band 88-89°F represents the most likely competing outcome if the high falls just short of the threshold.

Lines Analysis: Houston, Late May, and the 90-Degree Line

Houston’s late May climatology puts the city right at this threshold. Daily highs in the final week of May historically average near 88-90°F at Bush Intercontinental Airport, the standard observing site. A setup that favors the 90°F outcome typically requires low overnight humidity recovery, minimal cloud cover, and southerly flow that doesn’t bring marine layer suppression from the Gulf. When those conditions align, Houston clears 90°F routinely by late May. The market’s 54.5% lean reflects that baseline probability.

The conditions that keep the high at 89°F or below are real. Gulf moisture surges can cap afternoon heating even on sunny days. A weak shortwave trough or stalled boundary in the region can hold surface temps just below that round number. The 88-89°F band is the single most dangerous competitor to the 90°F outcome because Houston forecasts at this time of year cluster tightly around that range. A forecast of 90°F from NWS is not a guarantee of 90°F observed.

Signals to Monitor

• The National Weather Service Houston Area Forecast Discussion issued each morning and afternoon contains the most direct language about whether the May 28 high is expected to reach or exceed 90°F.
• The 12z and 18z GFS and NAM model runs for May 28 will sharpen the surface temperature forecast; any downward revision toward 88-89°F would push the market toward the alternative bands.
• Gulf moisture advection overnight into May 28 is the primary suppression risk; a dewpoint rise above 70°F into early morning typically caps afternoon highs.
• Clear skies and dry air in the morning hours favor a run at 90°F; cloud cover before noon is the single strongest brake on afternoon heating.
• The resolution timestamp of noon local time means only the morning heating ramp matters; late afternoon surges after noon do not count toward this market.

Here’s what the measurements are telling us: the market is pricing genuine uncertainty, not a settled outcome. Total volume of $10,970 is thin enough that the next NWS forecast discussion or a 6-hour model update could reprice this contract by 5-8 points in either direction. The data doesn’t care about the politics of climate or seasonal expectations. The 90°F bar either gets crossed before noon on May 28 or it doesn’t. Right now, the market says it probably does, but it’s not confident.

LINES VERDICT

SLIGHT LEAN TOWARD NINETY

Houston’s late May climatology and the current forecast setup support the 90°F outcome as the most likely single result, but the margin is thin and the noon resolution cutoff limits the heating window significantly.

What the market says: At 54.5% implied probability, traders price this as a slight lean toward 90°F or higher with real uncertainty on both sides. Thin volume means any NWS forecast update before May 28 morning could swing this contract several points.

Key unknown: The National Weather Service Houston Area Forecast Discussion to be issued on the morning of May 28 is the single data point that will reprice this contract. If that forecast shows a high of 89°F or below before the noon resolution window closes, the alternative bands gain fast.

Scientific Context

Houston’s late May temperature climatology clusters tightly between 87°F and 92°F for daily highs at Bush Intercontinental. The 90°F threshold falls near the median of that range for the last week of May, meaning the base rate probability of hitting 90°F on any given day in this window sits close to 50%. The market’s current 54.5% lean is consistent with a forecast that shows a slight positive bias toward the threshold without a clear 90°F-or-above lock. The noon resolution cutoff is the structural factor that matters most here. Houston regularly reaches its daily high between 2 and 4 PM local time. A noon cutoff means the market is pricing whether the city reaches 90°F during the morning heating ramp, not the full afternoon peak, which is a meaningfully harder ask.