How Temperature Markets Settle

The NWS Climatological Report (CLI) is the official daily weather summary for a station. It includes the day's official high temperature, low temperature, and average — calculated from raw sensor data (one-minute observations) without the additional rounding layers that affect publicly displayed temperatures.

Critically, CLI data has undergone NWS review. Faulty sensor readings are adjusted or removed. Temporary station outages are noted. This is what makes it the authoritative record.

The CLI is why you might watch a temperature all day and see 70°F displayed, but the official record settles at 69°F or 71°F. The displayed value went through the rounding pipeline; the CLI used raw sensor data.

Kalshi temperature markets settle based on NWS CLI data. When the CLI report is published for the observation day, Kalshi determines which bracket the official high or low falls into and resolves contracts accordingly.

Settlement typically occurs in the morning window (6-9am ET) the day after the observation day. minuteTemp records settlement outcomes from Kalshi's API, tracking which markets resolved and at what value.

For example, if a Kalshi market asks "Will NYC's high be above 75°F?" and the CLI reports an official high of 74°F, the "No" contracts pay out — regardless of whether real-time observations briefly showed 75°F or 76°F during the day.

Polymarket temperature markets also reference official weather data for settlement. The specific resolution mechanism may vary by market — check each market's resolution criteria on Polymarket for the exact data source and rules.

In general, Polymarket temperature markets use official government weather records (typically NWS CLI for US cities) as their settlement source. The resolution process may take slightly longer than Kalshi's.

It's common for the CLI to report a high or low that differs from what you tracked in real-time. This happens because:

• •Rounding differences: Real-time data goes through the F→C→F rounding pipeline; CLI uses raw sensor values
• •Sensor corrections: NWS may remove outlier readings from a malfunctioning sensor
• •Averaging differences: CLI uses 2-minute averaged one-minute data; public feeds may use instantaneous or differently averaged values

• •Station outages: If a station goes offline during the observation period, the CLI may note missing data. Market resolution rules vary by platform for these scenarios.
• •Corrected readings: Occasionally the NWS corrects a CLI after initial publication. Some platforms have provisions for amended reports.
• •Multi-station cities: Different stations may report different temperatures. Know which station the market references — e.g., NYC markets typically reference Central Park (KNYC), not LaGuardia (KLGA) or JFK (KJFK).