National Weather Service and NOAA guidance currently points to a Chicago high near 81°F on August 18, driven by a cooler-than-normal air mass and lingering cloud cover that has suppressed daytime heating relative to the 82.5°F climatological average. Recent model runs and surface observations show maximum temperatures holding in the upper 70s to low 80s amid weak southerly flow and higher dew points that limit diurnal rise, consistent with the market’s heavy weighting toward the 80–81°F bin. Forecasters note minimal afternoon mixing and no strong warm advection expected before sunset, keeping the 82–83°F outcome as a secondary possibility only if skies clear more than anticipated. Updated NWS briefings and next model cycle remain the key near-term catalysts.
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 18?
Highest temperature in Chicago on August 18?
80-81°F 53%
82-83°F 30%
78-79°F 10%
84-85°F 6%
NEW
$10,602 Vol.
NEW
$10,602 Vol.
Aug 18, 2026
71°F or below
<1%
72-73°F
<1%
74-75°F
<1%
76-77°F
2%
78-79°F
10%
80-81°F
53%
82-83°F
30%
84-85°F
6%
86-87°F
2%
88-89°F
<1%
90°F or higher
<1%
80-81°F 53%
82-83°F 30%
78-79°F 10%
84-85°F 6%
NEW
$10,602 Vol.
NEW
$10,602 Vol.
Aug 18, 2026
71°F or below
$25 Vol.
<1%
72-73°F
$233 Vol.
<1%
74-75°F
$3,000 Vol.
<1%
76-77°F
$387 Vol.
2%
78-79°F
$1,075 Vol.
10%
80-81°F
$2,096 Vol.
53%
82-83°F
$2,279 Vol.
30%
84-85°F
$614 Vol.
6%
86-87°F
$494 Vol.
2%
88-89°F
$302 Vol.
<1%
90°F or higher
$100 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 18 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 and NOAA guidance currently points to a Chicago high near 81°F on August 18, driven by a cooler-than-normal air mass and lingering cloud cover that has suppressed daytime heating relative to the 82.5°F climatological average. Recent model runs and surface observations show maximum temperatures holding in the upper 70s to low 80s amid weak southerly flow and higher dew points that limit diurnal rise, consistent with the market’s heavy weighting toward the 80–81°F bin. Forecasters note minimal afternoon mixing and no strong warm advection expected before sunset, keeping the 82–83°F outcome as a secondary possibility only if skies clear more than anticipated. Updated NWS briefings and next model cycle remain the key near-term catalysts.
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 18 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 18 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 16, 2026, 9:56 PM ET
Volume
$10,602End Date
Aug 18, 2026Market Opened
Aug 16, 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 18 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 and NOAA guidance currently points to a Chicago high near 81°F on August 18, driven by a cooler-than-normal air mass and lingering cloud cover that has suppressed daytime heating relative to the 82.5°F climatological average. Recent model runs and surface observations show maximum temperatures holding in the upper 70s to low 80s amid weak southerly flow and higher dew points that limit diurnal rise, consistent with the market’s heavy weighting toward the 80–81°F bin. Forecasters note minimal afternoon mixing and no strong warm advection expected before sunset, keeping the 82–83°F outcome as a secondary possibility only if skies clear more than anticipated. Updated NWS briefings and next model cycle remain the key near-term catalysts.
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 18 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 18 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
$10,602End Date
Aug 18, 2026Market Opened
Aug 16, 2026, 9:56 PM ETResolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDResolver
0x69c47De9D...National Weather Service and NOAA guidance currently points to a Chicago high near 81°F on August 18, driven by a cooler-than-normal air mass and lingering cloud cover that has suppressed daytime heating relative to the 82.5°F climatological average. Recent model runs and surface observations show maximum temperatures holding in the upper 70s to low 80s amid weak southerly flow and higher dew points that limit diurnal rise, consistent with the market’s heavy weighting toward the 80–81°F bin. Forecasters note minimal afternoon mixing and no strong warm advection expected before sunset, keeping the 82–83°F outcome as a secondary possibility only if skies clear more than anticipated. Updated NWS briefings and next model cycle remain the key near-term catalysts.
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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