Seasonal-milestone markets — first freeze, last frost, first measurable snow — are questions about the date of a first crossing, and the historical record at a given station gives a tight distribution for that date. Overlay the seasonal pattern in play and a warming trend and you have a well-founded probability weeks ahead. These markets are usually priced off whatever the weather did last week, which has almost nothing to do with it.
Markets on Polymarket where first-freeze & last-frost date distribution is the natural play:
