If you've ever lost a Kalshi temperature bet you thought was a lock, this article is for you. Most traders know the basics: Kalshi temperature markets settle based on the National Weather Service. But the details of how that settlement works — the specific station, the reporting window, the rounding — are where money gets made and lost.
Every Kalshi temperature market resolves based on one document: the NWS Daily Climate Summary, also called the CLI report. Not AccuWeather, not your iPhone weather app, not The Weather Channel — CLI and CLI only.
The CLI report is generated from data collected at a specific ASOS (Automated Surface Observing System) station at each city's designated airport. For example: Chicago uses Midway Airport (KMDW), Los Angeles uses LAX (KLAX), Miami uses Miami International (KMIA).
Each station has its own microclimate. Midway Airport in Chicago doesn't experience the same temperature as downtown. LAX sits right on the coast where marine layer and sea breezes can create conditions dramatically different from inland LA. The temperature your weather app shows for "Los Angeles" might be pulled from a completely different location.
The NWS Climate Summary reports the daily high temperature based on local standard time — not daylight saving time. During DST (roughly March through November for most of the US), this creates a reporting window that runs from 1:00 AM to 12:59 AM the following day in local clock time. A late-night temperature spike can land in a different calendar day than you'd expect.
ASOS stations record temperature every minute. The reported high is the maximum one-minute average during the reporting period. The reported temperature is rounded to the nearest whole degree Fahrenheit. NWS uses standard rounding: 0.5 rounds up. A reading of 72.5°F becomes 73°F in the CLI report, while 72.4°F becomes 72°F.
On Kalshi, brackets are defined in whole degrees (e.g., "72–73°F"). That means the difference between 72.4°F and 72.5°F is the difference between landing in the 72–73 bracket and the 73–74 bracket.
ASOS stations record temperature in Celsius. The CLI report publishes in Fahrenheit. That conversion (multiply by 1.8, add 32) happens before the number you see, and it introduces its own rounding step. The Celsius-to-Fahrenheit conversion creates uneven rounding boundaries. Some Fahrenheit degree transitions require a larger Celsius change to cross, while others can be triggered by the smallest measurable increment. This is pure measurement noise that no forecast model accounts for.
On top of the conversion, NWS uses standard rounding on the Fahrenheit result: 0.5 rounds up. The combination of these two layers means the path from actual air temperature to the number in the CLI report has multiple points where tiny differences cascade into bracket-shifting outcomes.
The NWS typically releases the Daily Climate Summary the morning after the market date, usually between 6:00 AM and 9:00 AM local time. Kalshi settles markets after this report is published. Kalshi's rules specify that the first published CLI report determines settlement, not any subsequent corrections.
Airport heat islands: Concrete runways and tarmac absorb heat and radiate it back, sometimes pushing the ASOS temperature a degree or two above what you'd measure in a nearby park. Sensor placement and maintenance can also introduce subtle biases that shift over months or years.
Always know your station. Before trading any city, look up the specific ASOS station Kalshi uses. Respect the rounding boundary — if your forecast puts the temperature within half a degree of a bracket boundary, the outcome is essentially random. Same-day markets reward real-time awareness. Settlement does not equal forecast.