National Weather Service guidance and short-range ensemble models currently project a daytime high near 79°F for Chicago on May 18, driven by southerly flow ahead of a warm front that will advect warmer air from the Gulf region. This setup places readings several degrees above the May 18 climatological normal of 71°F and supports the market’s leading 74.5% implied probability for a high of 78°F or above. Consistent model agreement and a modest severe-weather risk noted by the Storm Prediction Center further anchor trader sentiment. Any meaningful downward revision would require an unexpected cold-air intrusion or major shift in steering patterns, though the short forecast horizon and stable synoptic setup make such changes unlikely before resolution. Updated NWS guidance over the next 24 hours will refine the exact maximum.
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 May 18?
Highest temperature in Chicago on May 18?
78°F or higher 73%
76-77°F 16%
74-75°F 4.4%
72-73°F 1.3%
NEW
$54,126 Vol.
NEW
$54,126 Vol.
May 18, 2026
59°F or below
<1%
60-61°F
<1%
62-63°F
<1%
64-65°F
<1%
66-67°F
<1%
68-69°F
<1%
70-71°F
<1%
72-73°F
1%
74-75°F
4%
76-77°F
16%
78°F or higher
73%
78°F or higher 73%
76-77°F 16%
74-75°F 4.4%
72-73°F 1.3%
NEW
$54,126 Vol.
NEW
$54,126 Vol.
May 18, 2026
59°F or below
$30,252 Vol.
<1%
60-61°F
$7,919 Vol.
<1%
62-63°F
$1,173 Vol.
<1%
64-65°F
$1,892 Vol.
<1%
66-67°F
$1,142 Vol.
<1%
68-69°F
$866 Vol.
<1%
70-71°F
$1,462 Vol.
<1%
72-73°F
$1,957 Vol.
1%
74-75°F
$1,397 Vol.
4%
76-77°F
$2,626 Vol.
16%
78°F or higher
$3,490 Vol.
73%
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 May '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day by the Forecast for the Chicago O'Hare Intl Airport Station once information is finalized, 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 to "Yes" until all data for this date has been finalized.
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.
Any revisions to temperatures recorded after data is finalized for this market's timeframe will not be considered for this market's resolution.National Weather Service guidance and short-range ensemble models currently project a daytime high near 79°F for Chicago on May 18, driven by southerly flow ahead of a warm front that will advect warmer air from the Gulf region. This setup places readings several degrees above the May 18 climatological normal of 71°F and supports the market’s leading 74.5% implied probability for a high of 78°F or above. Consistent model agreement and a modest severe-weather risk noted by the Storm Prediction Center further anchor trader sentiment. Any meaningful downward revision would require an unexpected cold-air intrusion or major shift in steering patterns, though the short forecast horizon and stable synoptic setup make such changes unlikely before resolution. Updated NWS guidance over the next 24 hours will refine the exact maximum.
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 May '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day by the Forecast for the Chicago O'Hare Intl Airport Station once information is finalized, 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 to "Yes" until all data for this date has been finalized.
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.
Any revisions to temperatures recorded after data is finalized for this market's timeframe will not be considered for this market's resolution.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day by the Forecast for the Chicago O'Hare Intl Airport Station once information is finalized, 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 to "Yes" until all data for this date has been finalized.
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.
Any revisions to temperatures recorded after data is finalized for this market's timeframe will not be considered for this market's resolution.
Market Opened: May 16, 2026, 12:04 AM ET
Volume
$54,126End Date
May 18, 2026Market Opened
May 16, 2026, 12:04 AM ETResolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDThis 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 May '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day by the Forecast for the Chicago O'Hare Intl Airport Station once information is finalized, 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 to "Yes" until all data for this date has been finalized.
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.
Any revisions to temperatures recorded after data is finalized for this market's timeframe will not be considered for this market's resolution.National Weather Service guidance and short-range ensemble models currently project a daytime high near 79°F for Chicago on May 18, driven by southerly flow ahead of a warm front that will advect warmer air from the Gulf region. This setup places readings several degrees above the May 18 climatological normal of 71°F and supports the market’s leading 74.5% implied probability for a high of 78°F or above. Consistent model agreement and a modest severe-weather risk noted by the Storm Prediction Center further anchor trader sentiment. Any meaningful downward revision would require an unexpected cold-air intrusion or major shift in steering patterns, though the short forecast horizon and stable synoptic setup make such changes unlikely before resolution. Updated NWS guidance over the next 24 hours will refine the exact maximum.
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 May '26.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day by the Forecast for the Chicago O'Hare Intl Airport Station once information is finalized, 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 to "Yes" until all data for this date has been finalized.
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.
Any revisions to temperatures recorded after data is finalized for this market's timeframe will not be considered for this market's resolution.
The resolution source for this market will be information from Wunderground, specifically the highest temperature recorded for all times on this day by the Forecast for the Chicago O'Hare Intl Airport Station once information is finalized, 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 to "Yes" until all data for this date has been finalized.
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.
Any revisions to temperatures recorded after data is finalized for this market's timeframe will not be considered for this market's resolution.
Volume
$54,126End Date
May 18, 2026Market Opened
May 16, 2026, 12:04 AM ETResolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDNational Weather Service guidance and short-range ensemble models currently project a daytime high near 79°F for Chicago on May 18, driven by southerly flow ahead of a warm front that will advect warmer air from the Gulf region. This setup places readings several degrees above the May 18 climatological normal of 71°F and supports the market’s leading 74.5% implied probability for a high of 78°F or above. Consistent model agreement and a modest severe-weather risk noted by the Storm Prediction Center further anchor trader sentiment. Any meaningful downward revision would require an unexpected cold-air intrusion or major shift in steering patterns, though the short forecast horizon and stable synoptic setup make such changes unlikely before resolution. Updated NWS guidance over the next 24 hours will refine the exact maximum.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · Updated
Beware of external links.
Beware of external links.
Frequently Asked Questions