Latest National Weather Service and AccuWeather forecasts project a daytime high near 79°F for Chicago on May 18, well above the 1991–2020 normal of 71°F for that date. This outlook stems from a broad warm-air advection pattern across the Midwest, with limited cloud cover and light winds allowing strong solar heating. Ensemble model runs show little spread, keeping the probability of reaching or exceeding 78°F near 89 percent in the market. Updated guidance over the past 48 hours has held steady without signals of a cooler air mass arriving in time, though minor afternoon convection could trim the peak by 1–2°F if it develops earlier than currently expected.
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 88%
76-77°F 11%
74-75°F 2.1%
72-73°F <1%
NEW
$14,512 Vol.
NEW
$14,512 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
2%
76-77°F
11%
78°F or higher
88%
78°F or higher 88%
76-77°F 11%
74-75°F 2.1%
72-73°F <1%
NEW
$14,512 Vol.
NEW
$14,512 Vol.
May 18, 2026
59°F or below
$1,124 Vol.
<1%
60-61°F
$7,062 Vol.
<1%
62-63°F
$830 Vol.
<1%
64-65°F
$1,027 Vol.
<1%
66-67°F
$779 Vol.
<1%
68-69°F
$475 Vol.
<1%
70-71°F
$556 Vol.
1%
72-73°F
$544 Vol.
1%
74-75°F
$573 Vol.
2%
76-77°F
$771 Vol.
11%
78°F or higher
$987 Vol.
88%
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.Latest National Weather Service and AccuWeather forecasts project a daytime high near 79°F for Chicago on May 18, well above the 1991–2020 normal of 71°F for that date. This outlook stems from a broad warm-air advection pattern across the Midwest, with limited cloud cover and light winds allowing strong solar heating. Ensemble model runs show little spread, keeping the probability of reaching or exceeding 78°F near 89 percent in the market. Updated guidance over the past 48 hours has held steady without signals of a cooler air mass arriving in time, though minor afternoon convection could trim the peak by 1–2°F if it develops earlier than currently expected.
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
$14,512End 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.Latest National Weather Service and AccuWeather forecasts project a daytime high near 79°F for Chicago on May 18, well above the 1991–2020 normal of 71°F for that date. This outlook stems from a broad warm-air advection pattern across the Midwest, with limited cloud cover and light winds allowing strong solar heating. Ensemble model runs show little spread, keeping the probability of reaching or exceeding 78°F near 89 percent in the market. Updated guidance over the past 48 hours has held steady without signals of a cooler air mass arriving in time, though minor afternoon convection could trim the peak by 1–2°F if it develops earlier than currently expected.
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
$14,512End Date
May 18, 2026Market Opened
May 16, 2026, 12:04 AM ETResolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDLatest National Weather Service and AccuWeather forecasts project a daytime high near 79°F for Chicago on May 18, well above the 1991–2020 normal of 71°F for that date. This outlook stems from a broad warm-air advection pattern across the Midwest, with limited cloud cover and light winds allowing strong solar heating. Ensemble model runs show little spread, keeping the probability of reaching or exceeding 78°F near 89 percent in the market. Updated guidance over the past 48 hours has held steady without signals of a cooler air mass arriving in time, though minor afternoon convection could trim the peak by 1–2°F if it develops earlier than currently expected.
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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