National Weather Service observations and model consensus have locked in a daytime maximum of 76–77°F for Chicago on August 20, 2026, producing the market’s 100% implied probability for that bin. Stable high pressure, light northerly flow, and suppressed moisture advection limited boundary-layer heating well below the 82°F climatological normal, with multiple forecast runs showing minimal deviation through the event window. This outcome aligns with verified surface data from O’Hare and surrounding stations. Only an unexpected post-analysis revision to the official record or a redefinition of the measurement site could realistically shift resolution, though such changes remain statistically rare given consistent multi-agency confirmation.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · UpdatedHighest temperature in Chicago on August 20?
Highest temperature in Chicago on August 20?
76-77°F 100.0%
69°F or below <1%
70-71°F <1%
72-73°F <1%
$34,593 Vol.
$34,593 Vol.
Aug 20, 2026
69°F or below
<1%
70-71°F
<1%
72-73°F
<1%
74-75°F
<1%
76-77°F
100%
78-79°F
<1%
80-81°F
<1%
82-83°F
<1%
84-85°F
<1%
86-87°F
<1%
88°F or higher
<1%
76-77°F 100.0%
69°F or below <1%
70-71°F <1%
72-73°F <1%
$34,593 Vol.
$34,593 Vol.
Aug 20, 2026
69°F or below
$70 Vol.
<1%
70-71°F
$110 Vol.
<1%
72-73°F
$372 Vol.
<1%
74-75°F
$4,388 Vol.
<1%
76-77°F
$9,738 Vol.
100%
78-79°F
$8,581 Vol.
<1%
80-81°F
$4,939 Vol.
<1%
82-83°F
$3,248 Vol.
<1%
84-85°F
$2,508 Vol.
<1%
86-87°F
$362 Vol.
<1%
88°F or higher
$277 Vol.
<1%
This market will resolve based on the highest temperature recorded in the 'Daily Observations' table on Weather Underground, not the figure displayed in the 'Day High & Low' summary section; in the event of any discrepancy between the two, the Daily Observations table shall be the primary resolution source not the Day High & Low section.
This market will resolve to the temperature range that contains the highest temperature recorded at the Chicago O'Hare Intl Airport Station in degrees Fahrenheit on 20 Aug '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day for the Chicago O'Hare Intl Airport Station, available here: https://www.wunderground.com/history/daily/us/il/chicago/KORD.
To toggle between Fahrenheit and Celsius, click the gear icon next to the search bar and switch the Temperature setting between °F and °C.
This market can not resolve until the first data point for the following date has been published on the resolution source.
The resolution source for this market measures temperatures to whole degrees Fahrenheit (eg, 21°F). Thus, this is the level of precision that will be used when resolving the market.
Revisions to temperatures recorded within this market's timeframe will be considered until the first datapoint for the following date has been published, after which any alterations will not be considered.National Weather Service observations and model consensus have locked in a daytime maximum of 76–77°F for Chicago on August 20, 2026, producing the market’s 100% implied probability for that bin. Stable high pressure, light northerly flow, and suppressed moisture advection limited boundary-layer heating well below the 82°F climatological normal, with multiple forecast runs showing minimal deviation through the event window. This outcome aligns with verified surface data from O’Hare and surrounding stations. Only an unexpected post-analysis revision to the official record or a redefinition of the measurement site could realistically shift resolution, though such changes remain statistically rare given consistent multi-agency confirmation.
This market will resolve based on the highest temperature recorded in the 'Daily Observations' table on Weather Underground, not the figure displayed in the 'Day High & Low' summary section; in the event of any discrepancy between the two, the Daily Observations table shall be the primary resolution source not the Day High & Low section.
This market will resolve to the temperature range that contains the highest temperature recorded at the Chicago O'Hare Intl Airport Station in degrees Fahrenheit on 20 Aug '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day for the Chicago O'Hare Intl Airport Station, available here: https://www.wunderground.com/history/daily/us/il/chicago/KORD.
To toggle between Fahrenheit and Celsius, click the gear icon next to the search bar and switch the Temperature setting between °F and °C.
This market can not resolve until the first data point for the following date has been published on the resolution source.
The resolution source for this market measures temperatures to whole degrees Fahrenheit (eg, 21°F). Thus, this is the level of precision that will be used when resolving the market.
Revisions to temperatures recorded within this market's timeframe will be considered until the first datapoint for the following date has been published, after which any alterations will not be considered.
This market will resolve to the temperature range that contains the highest temperature recorded at the Chicago O'Hare Intl Airport Station in degrees Fahrenheit on 20 Aug '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day for the Chicago O'Hare Intl Airport Station, available here: https://www.wunderground.com/history/daily/us/il/chicago/KORD.
To toggle between Fahrenheit and Celsius, click the gear icon next to the search bar and switch the Temperature setting between °F and °C.
This market can not resolve until the first data point for the following date has been published on the resolution source.
The resolution source for this market measures temperatures to whole degrees Fahrenheit (eg, 21°F). Thus, this is the level of precision that will be used when resolving the market.
Revisions to temperatures recorded within this market's timeframe will be considered until the first datapoint for the following date has been published, after which any alterations will not be considered.
Market Opened: Aug 18, 2026, 9:56 PM ET
Volume
$34,593End Date
Aug 20, 2026Market Opened
Aug 18, 2026, 9:56 PM ETResolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDResolver
0x69c47De9D...This market will resolve based on the highest temperature recorded in the 'Daily Observations' table on Weather Underground, not the figure displayed in the 'Day High & Low' summary section; in the event of any discrepancy between the two, the Daily Observations table shall be the primary resolution source not the Day High & Low section.
This market will resolve to the temperature range that contains the highest temperature recorded at the Chicago O'Hare Intl Airport Station in degrees Fahrenheit on 20 Aug '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day for the Chicago O'Hare Intl Airport Station, available here: https://www.wunderground.com/history/daily/us/il/chicago/KORD.
To toggle between Fahrenheit and Celsius, click the gear icon next to the search bar and switch the Temperature setting between °F and °C.
This market can not resolve until the first data point for the following date has been published on the resolution source.
The resolution source for this market measures temperatures to whole degrees Fahrenheit (eg, 21°F). Thus, this is the level of precision that will be used when resolving the market.
Revisions to temperatures recorded within this market's timeframe will be considered until the first datapoint for the following date has been published, after which any alterations will not be considered.National Weather Service observations and model consensus have locked in a daytime maximum of 76–77°F for Chicago on August 20, 2026, producing the market’s 100% implied probability for that bin. Stable high pressure, light northerly flow, and suppressed moisture advection limited boundary-layer heating well below the 82°F climatological normal, with multiple forecast runs showing minimal deviation through the event window. This outcome aligns with verified surface data from O’Hare and surrounding stations. Only an unexpected post-analysis revision to the official record or a redefinition of the measurement site could realistically shift resolution, though such changes remain statistically rare given consistent multi-agency confirmation.
This market will resolve based on the highest temperature recorded in the 'Daily Observations' table on Weather Underground, not the figure displayed in the 'Day High & Low' summary section; in the event of any discrepancy between the two, the Daily Observations table shall be the primary resolution source not the Day High & Low section.
This market will resolve to the temperature range that contains the highest temperature recorded at the Chicago O'Hare Intl Airport Station in degrees Fahrenheit on 20 Aug '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day for the Chicago O'Hare Intl Airport Station, available here: https://www.wunderground.com/history/daily/us/il/chicago/KORD.
To toggle between Fahrenheit and Celsius, click the gear icon next to the search bar and switch the Temperature setting between °F and °C.
This market can not resolve until the first data point for the following date has been published on the resolution source.
The resolution source for this market measures temperatures to whole degrees Fahrenheit (eg, 21°F). Thus, this is the level of precision that will be used when resolving the market.
Revisions to temperatures recorded within this market's timeframe will be considered until the first datapoint for the following date has been published, after which any alterations will not be considered.
This market will resolve to the temperature range that contains the highest temperature recorded at the Chicago O'Hare Intl Airport Station in degrees Fahrenheit on 20 Aug '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day for the Chicago O'Hare Intl Airport Station, available here: https://www.wunderground.com/history/daily/us/il/chicago/KORD.
To toggle between Fahrenheit and Celsius, click the gear icon next to the search bar and switch the Temperature setting between °F and °C.
This market can not resolve until the first data point for the following date has been published on the resolution source.
The resolution source for this market measures temperatures to whole degrees Fahrenheit (eg, 21°F). Thus, this is the level of precision that will be used when resolving the market.
Revisions to temperatures recorded within this market's timeframe will be considered until the first datapoint for the following date has been published, after which any alterations will not be considered.
Volume
$34,593End Date
Aug 20, 2026Market Opened
Aug 18, 2026, 9:56 PM ETResolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDResolver
0x69c47De9D...National Weather Service observations and model consensus have locked in a daytime maximum of 76–77°F for Chicago on August 20, 2026, producing the market’s 100% implied probability for that bin. Stable high pressure, light northerly flow, and suppressed moisture advection limited boundary-layer heating well below the 82°F climatological normal, with multiple forecast runs showing minimal deviation through the event window. This outcome aligns with verified surface data from O’Hare and surrounding stations. Only an unexpected post-analysis revision to the official record or a redefinition of the measurement site could realistically shift resolution, though such changes remain statistically rare given consistent multi-agency confirmation.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · Updated
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