Glossary of Kalshi and Polymarket weather terms

40 words Kalshi's and Polymarket's daily temperature markets are settled in, each in a sentence or two, with the primary source it comes from. Checked October 26, 2026.

The climate report

CLI report (NWS Daily Climate Report): The National Weather Service's daily summary for one station: the day's high and low with their times, the normal, the record and precipitation. Each station's report has a code: CLINYC is Central Park's, CLIMDW is Chicago Midway's. Kalshi's rules name every city by that code.; CLIMDW for Chicago settles on Midway (KMDW), not O'Hare.; How to read the climate report; Source: NWS Instruction 10-1004, Climate Records, section 4.1; Central Park's climate report (CLINYC)
Preliminary climate report: A climate report issued during the day, marked "VALID TODAY AS OF 0400 PM LOCAL TIME" (or another hour), with the high so far. The NWS issues one in the late afternoon, typically 3:00 to 5:30 PM local time. It doesn't settle the market, and the final report can be higher.; Source: NWS Instruction 10-1004, section 4.1.2; Kalshi contract terms (GLOBALTEMPERATURE)
Final climate report: The climate report for the whole day, which the NWS issues between 12:30 and 5:00 AM local time the next morning. Kalshi's contract terms use "the first official non-preliminary report"; a correction issued later doesn't change a market that has expired.; Miami, Aug 29, 2026: the 4:24 AM report said 90°F and a 5:10 AM report said 85°F. The market settled on 90.; Source: NWS Instruction 10-1004, section 4.1.2; Kalshi contract terms (GLOBALTEMPERATURE)
Record high: The highest high for that calendar date since the station's record began, with the year it was set. An R after a value in the climate report means a record was set or tied that day.; Source: NWS Instruction 10-1004, section 4.1.3
Normal high: The average high for the date over 1991 to 2020, the climate normals the NWS reports print today. The report's departure column is the day's high minus it.; Source: NOAA NCEI U.S. Climate Normals; NWS Instruction 10-1004, section 4.1.3
MM (missing): What the climate report prints when a value is missing, including a missing time of the high.; Source: NWS Instruction 10-1004, section 4.1.3
Iowa Environmental Mesonet (IEM): Iowa State University's public archive of National Weather Service products and station reports. Almanac reads past climate reports and METARs from it; the NWS's own site keeps about a week of reports.; Source: Iowa Environmental Mesonet

Station readings

ASOS: The Automated Surface Observing System, the instruments at the settlement stations. Its sensor samples about every 10 seconds, keeps whole degrees Fahrenheit, and reports them to the world in degrees Celsius.; Source: NWS Chicago: weather observations FAQ; NWS ASOS program; ASOS User's Guide
METAR: A station's routine weather report: about once an hour (Central Park's go out at 51 minutes past), plus specials (SPECI) when the weather changes. Its body gives the temperature in whole degrees Celsius; its remarks give the exact reading.; METAR KNYC 191151Z AUTO 00000KT 10SM CLR 09/07 A3050 RMK AO2 SLP321 T00890067 10094 20083 55002 $; METAR decoder; Source: aviationweather.gov data API; NWS Chicago: weather observations FAQ
T-group: The METAR remark with the temperature and dew point in tenths of a degree Celsius: T02330178 is 23.3°C and 17.8°C, and a 1 in place of the first 0 means below zero. Because ASOS keeps whole °F, round(°C × 9/5 + 32) gives the station's exact reading.; T00890067: 8.9°C × 9/5 + 32 = 48.02, so 48°F.; Decode a METAR; Source: NWS Chicago: weather observations FAQ
6-hour maximum group: 1snTTT in a METAR's remarks: the highest temperature of the previous 6 hours, in tenths of a degree Celsius, on the reports near 00, 06, 12 and 18 UTC. It catches a peak that fell between hourly reports. 10094 is 9.4°C.; Source: NWS Chicago: weather observations FAQ; ASOS User's Guide
24-hour maximum and minimum group: 4snTTTsnTTT: the highest and lowest temperature of the previous 24 hours, on the report nearest local standard midnight. 401390050 is a 13.9°C high and a 5.0°C low: 57°F and 41°F.; Source: ASOS User's Guide
High so far: The day's highest exact reading up to now, from the T-groups and the 6- and 24-hour maximum groups. The official high can still be higher (a peak between reports) or, now and then, lower (when the NWS discards a reading).; Source: NWS Chicago: weather observations FAQ
ICAO station id: A station's four-letter id; US ids start with K. KNYC is Central Park, KMDW is Chicago Midway.; Source: aviationweather.gov data API
Highest hourly reading (Polymarket US): What Polymarket's US temperature markets resolve on, as their rules say: the highest temperature among the station's readings for the day, in whole degrees, as published. Kalshi settles on the day's official high from the climate report, which can be higher than any one reading.; How the two exchanges' days compare; Source: Polymarket's public market data and each event's rules

The day and the clock

Local standard time (LST): The clock without daylight saving. The climate day runs midnight to midnight local standard time and doesn't move for daylight saving, so in summer it runs 1 AM to 1 AM on the local clock. The report's time column is in LST too.; Settlement window for any city and date; Source: NWS Chicago: weather observations FAQ
Climate day: The 24 hours a station's daily high is taken over: midnight to midnight local standard time. During daylight saving, a warm reading at 12:30 AM on the clock still counts toward the day before.; Source: NWS Chicago: weather observations FAQ
Daylight saving time: Clocks one hour ahead, from March to November in most of the US. The climate day ignores it; Phoenix keeps standard time all year, so its day is midnight to midnight on the clock.; Source: NWS Chicago: weather observations FAQ
Close time: When trading stops. Since the Aug 14, 2026 events it is 00:00 local standard time after the day in every city, which is 1:00 AM on the clock during daylight saving, not the 11:59 PM the market's close-condition text says.; Source: Each market's close time, Kalshi's public market data; Kalshi contract terms (GLOBALTEMPERATURE)
Local calendar day (Polymarket): Polymarket's temperature markets count the city's whole local day, midnight to midnight on the clock, daylight saving included. Kalshi's count midnight to midnight local standard time, so in summer Kalshi's day runs 1 AM to 1 AM.; Both days for any city and date; Source: Polymarket's public market data and each event's rules

Markets and brackets

Settlement source: Whose number decides the market. For Kalshi's daily highs the contract terms list The Weather Company first, then the National Weather Service; events before Aug 14, 2026 named the NWS climate report.; What changed on Aug 14, 2026; Source: Kalshi contract terms (GLOBALTEMPERATURE)
The Weather Company (weather.com/kalshi): The settlement source named by the rules since the Aug 14, 2026 events. Its settlement page lists each station-day as preliminary, final, revised or no report. Kalshi's value matched it on 1,541 of 1,541 settled days checked from Aug 14 to Oct 18, 2026.; Source: The Weather Company, weather.com/kalshi; Kalshi contract terms (GLOBALTEMPERATURE)
Bracket: One of the six yes-or-no markets for a city's day. Four are 2-degree ranges that include both ends ("65° to 66°" wins on 65 or 66); the other two are the tails.; Source: Kalshi contract terms (GLOBALTEMPERATURE)
Tail bracket: The bottom and top brackets, and they are strict: a cap of 65 wins only below 65 ("64° or below"), and a floor of 72 wins only above 72 ("73° or above").; Source: Kalshi contract terms ("above" means greater than)
strike_type, floor_strike and cap_strike: The fields in Kalshi's market data that say what a bracket wins on: strike_type is between, less or greater; floor_strike and cap_strike are its bounds. The bounds include both ends for a between bracket and exclude them for a tail, whatever the ticker letters say ("T65" and "T72" are both T).; Source: Kalshi API reference: markets
Series, event and market tickers: KXHIGHNY is New York City's series, KXHIGHNY-26OCT20 is its Oct 20, 2026 event, and KXHIGHNY-26OCT20-B65.5 is one bracket (B65.5 is the midpoint of 65 to 66). Read the station from the rules, not the series title: Louisville's series is titled "SATX".; Source: Kalshi API reference: markets
Settlement (expiration): When Kalshi decides the market from the source's number and pays $1 a contract to the winning side; usually about 7 AM local time the next morning. Expiration can be held while the source's number is in doubt.; Source: Kalshi contract terms (GLOBALTEMPERATURE); Each market's settlement time, Kalshi's public market data
Material error: Kalshi's term for a source value it judges wrong. From the Sep 3, 2026 events on, the rules say expiration may be held until a corrected value is published, and if none is, the markets resolve to the last fair price.; Can these markets be gamed?; Source: Each market's rules, Kalshi's public market data
Last fair price: The price Kalshi resolves every bracket to if no usable data arrives by the latest expiration date (a week after the event), under the rules' material-error clause.; Source: Each market's rules, Kalshi's public market data
Scalar settlement: A settlement at a fraction instead of $0 or $1. One Miami day (Apr 11, 2026) paid $0.01 on one bracket and $0.99 on its neighbour, a week late.; Source: Kalshi's public market data (KXHIGHMIA-26APR11)
Polymarket: A prediction market that lists daily highest- and lowest-temperature markets for US cities, in whole degrees Fahrenheit, and for cities around the world, in whole degrees Celsius. Each market's own rules name the station and how its reading is taken, and a share of the winning range pays $1.; Polymarket's New York market settles on LaGuardia (KLGA); Kalshi's settles on Central Park (KNYC).; Kalshi vs Polymarket, city by city; Source: Polymarket's public market data and each event's rules
Range (Polymarket): One of a Polymarket temperature market's answers: a 2°F range like 64-65°F in its US cities, a single degree like 18°C in its world cities, plus an open range at each end. The range the day's reading lands in pays $1 a share.; Source: Polymarket's public market data and each event's rules

Prices, fees and payouts

Bid and ask: The best price someone will pay for YES (the bid) and the best price someone will sell it for (the ask), in dollars per $1 contract: "0.5400" is 54¢. A bid of $0.0000 or an ask of $1.0000 means that side is empty, not a price.; Source: Kalshi API documentation
Taker fee: Kalshi's fee on an order that trades against a resting one: 0.07 × contracts × price × (1 − price), rounded up to the next cent, per order. These series charge no maker fee and no settlement fee.; 1 contract at 54¢: 0.07 × 0.54 × 0.46 = $0.0174, rounded up to 2¢.; Kalshi weather fees; Source: Kalshi Fee Schedule (effective Feb 5, 2026)
Break-even price: What an order cost per contract, fee included: (price × contracts + fee) ÷ contracts. It is the chance the contract must have of paying $1 for the order to come out even. One contract at 54¢ costs 56¢ with its 2¢ fee, so 56%.; Source: Kalshi Fee Schedule (effective Feb 5, 2026)
Polymarket taker fee: Polymarket's fee on weather markets, paid only by the side that takes a resting order: 0.05 × shares × price × (1 − price). It is largest at 50¢ ($1.25 per 100 shares) and makers pay nothing.; 100 shares at 30¢: 0.05 × 100 × 0.30 × 0.70 = $1.05.; Both exchanges' fees; Source: Polymarket documentation: fees

Forecasts and scores

Model bias: How far a forecast model's daily high runs above (hot) or below (cold) a station's official high, on average. It is large and station-specific: at LAX the ECMWF ensemble mean has run about 8°F hot.; Source: Open-Meteo previous model runs
Ensemble mean: The average of a model's many slightly different runs (its members), which forecasters use to smooth out any one run's noise.; Source: Open-Meteo previous model runs
Log loss: How surprised a forecast was by what happened: minus the natural log of the probability it gave the bracket that won, averaged over city-days. Lower is better. A forecast that gave the winner 30% scores 1.20 that day; one that gave it 50% scores 0.69.; Market vs models; Source: Almanac's backtest, Aug 20 to Oct 18, 2026
Brier score: The average squared gap between each bracket's probability and what it paid (1 or 0), over every bracket. Lower is better; it rewards being sure only when right.; Source: Almanac's backtest, Aug 20 to Oct 18, 2026

How the markets settle · How to read the climate report · METAR decoder

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