Official source is wunderground.com . We’ll use the midway weather station because wunderground supports calendar view for that station https://www.wunderground.com/calendar/us/il/chicago/KMDW
For the April 15 market as an example: If there are any readings after April 15 where the temperature is below 40 degrees Fahrenheit then that market will resolve as No. If we make it to June 1 and it has stayed above 40 then it resolves as Yes.
Same behavior for any other dates listed.
Update 2025-04-02 (PST) (AI summary of creator comment): - Post-Day Readings: Only temperature readings recorded after the end of the specified day count. In other words, a low temperature on the day itself (e.g., April 1) does not affect the market.
Example for April 1 Market: The April 1 low below 40°F does not trigger resolution. Only a reading below 40°F after April 1 (such as on April 2 or later) will be considered.
Resolution Impact: The market will continue to have the possibility of a different outcome until a qualifying low (post-day reading under 40°F) is recorded before the market’s close date.
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1.00We’ll use the midway weather station because wunderground supports calendar view for that station
Rules clarification: the low on April 1 was below 40, but that doesn’t affect the April 1 market. There has to be a low after the end of the day of April 1 to count as after April 1. As of 6:55am April 2 that hasn’t happened yet (temp was about 44 at midnight) so it’s still possible for the April 1 market to resolve as no. But if it does drop below 40 any time before June then the April 1 market will resolve as yes.