We pull the GEFS (31), ECMWF ENS (51), ICON-EPS (40), and GEM (21) ensemble systems from Open-Meteo โ roughly 143 possible futures per city. We don't average them into one number; we use the whole distribution.
For each Kalshi bracket, we count how many ensemble members land there. If 42 of 143 members say the high will be 72โ73ยฐF, that bracket has a 29% probability. Simple, honest math โ no hand-tuned weights.
If our probability is 29% and Kalshi is pricing the bracket at 20ยข, EV = +45%. Positive EV means the bracket is underpriced vs. our model. The opposite is also true โ we'll show you brackets the market is overvaluing.
Every time Kalshi settles a market, we record the error between our ensemble mean and the actual high. That bias gets subtracted from future forecasts for that city. After 1 PM local, if the observed temp is already higher than any member predicted, we clip the distribution upward.
Ensemble forecasts are not oracles. Brackets can and do settle at $0. Never risk what you can't lose. Track record below is raw โ no cherry-picking.
WeatherQuant is not financial advice. Ensemble forecasts are probabilistic โ they can be wrong. Kalshi markets carry real risk and can settle at $0.
Not affiliated with Kalshi, Inc. or the National Weather Service. Trade at your own risk.