Ensemble weather models from NOAA and ECMWF drive trader sentiment toward mid-60s highs for Chicago on March 21, with GFS and Canadian runs averaging 64-67°F at O'Hare, aligning with top market-implied odds of 21.5% for 64-65°F and 18% for 66-67°F. A strengthening southerly flow ahead of an approaching warm front supports potential upside to 70-71°F (17.5%), but divergent cloud cover forecasts and diurnally varying boundary layer mixing differentiate these tight bins—clearer skies could boost peaks by 3-5°F via enhanced insolation. Historical March volatility at O'Hare, with standard deviations of 10°F, plus 12z model updates expected soon, keep lower 70s viable while capping 74°F+ at under 10%. Traders watch hourly guidance for resolution thresholds.
Experimental AI-generated summary referencing Polymarket data · UpdatedHighest temperature in Chicago on March 21?
Highest temperature in Chicago on March 21?
64-65°F 18%
70-71°F 17%
72-73°F 16%
66-67°F 16%
59°F or below
9%
60-61°F
5%
62-63°F
3%
64-65°F
18%
66-67°F
16%
68-69°F
13%
70-71°F
17%
72-73°F
16%
74-75°F
7%
76-77°F
2%
78°F or higher
1%
64-65°F 18%
70-71°F 17%
72-73°F 16%
66-67°F 16%
59°F or below
9%
60-61°F
5%
62-63°F
3%
64-65°F
18%
66-67°F
16%
68-69°F
13%
70-71°F
17%
72-73°F
16%
74-75°F
7%
76-77°F
2%
78°F or higher
1%
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: Mar 17, 2026, 6:02 AM ET
Resolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDResolver
0x69c47De9D...Resolution Source
https://www.wunderground.com/history/daily/us/il/chicago/KORDResolver
0x69c47De9D...Ensemble weather models from NOAA and ECMWF drive trader sentiment toward mid-60s highs for Chicago on March 21, with GFS and Canadian runs averaging 64-67°F at O'Hare, aligning with top market-implied odds of 21.5% for 64-65°F and 18% for 66-67°F. A strengthening southerly flow ahead of an approaching warm front supports potential upside to 70-71°F (17.5%), but divergent cloud cover forecasts and diurnally varying boundary layer mixing differentiate these tight bins—clearer skies could boost peaks by 3-5°F via enhanced insolation. Historical March volatility at O'Hare, with standard deviations of 10°F, plus 12z model updates expected soon, keep lower 70s viable while capping 74°F+ at under 10%. Traders watch hourly guidance for resolution thresholds.
Experimental AI-generated summary referencing Polymarket data · Updated
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