Highest temperature in Chicago on Oct 4, 2026: PBE moves “69° or below” up to 34% from 21%
New forecast guidance reached the model between 20:00 UTC and 23:00 UTC on Oct 3. Same model version, later data cutoff: here is exactly which inputs changed.
Photo: J. Crocker · Attribution · Wikimedia Commons
69° or below · pbe-weather-maxtemp@1.1.0 · 20:00 UTC → 23:00 UTC
Highest temperature in Chicago on Oct 4, 2026?
69° or below · RESOLVED
- UPDATE · Oct 4 18:22Z PBE 1% pbe-weather-maxtemp-intraday@2.1.0 · data cutoff Oct 4 17:22Z
Quick read
- pbe-weather-maxtemp@1.1.0 moved “69° or below” from 21% to 34% (+13 pts).
- Later data cutoff: Oct 3 17:00Z → Oct 3 23:00Z; same model version, so the move reflects inputs, not a model change.
- Primary inputs changed: National Blend of Models forecast high.
- The Kalshi mid captured with each snapshot went from 4% to 5%.
What changed in the inputs
Between the snapshot captured at Oct 3 20:00Z (data cutoff Oct 3 17:00Z) and the one at Oct 3 23:00Z (cutoff Oct 3 23:00Z), the same model version — pbe-weather-maxtemp@1.1.0 — moved “69° or below” from 21% to 34%. The model inputs that changed: National Blend of Models forecast high from 71°F to 70°F.
| Input | Before | After | Primary |
|---|---|---|---|
| Guidance lead time | 18h | 12h | — |
| National Blend of Models forecast high | 71°F | 70°F | yes |
This page reports which stored inputs differ between two immutable forecasts. It does not claim why the underlying weather guidance changed.
The forecast path
Data table
| Time (UTC) | Source | Value % |
|---|---|---|
| Oct 3 18:31Z | Kalshi mid | 4 |
| Oct 3 18:45Z | PBE pbe-weather-maxtemp@1.1.0 | 21 |
| Oct 3 19:00Z | Kalshi mid | 4 |
| Oct 3 20:00Z | PBE pbe-weather-maxtemp@1.1.0 | 21 |
| Oct 3 20:00Z | Kalshi mid | 4 |
| Oct 3 21:00Z | Kalshi mid | 4 |
| Oct 3 21:30Z | Kalshi mid | 4 |
| Oct 3 22:00Z | Kalshi mid | 4 |
| Oct 3 22:15Z | Kalshi mid | 4 |
| Oct 3 22:30Z | Kalshi mid | 5 |
| Oct 3 23:00Z | PBE pbe-weather-maxtemp@1.1.0 | 34 |
| Oct 3 23:00Z | Kalshi mid | 5 |
The Kalshi mid captured with each snapshot went from 4% to 5%.
The two snapshots
| Earlier | Later | |
|---|---|---|
| Captured | Oct 3 20:00Z | Oct 3 23:00Z |
| Data cutoff | Oct 3 17:00Z | Oct 3 23:00Z |
| Guidance runs | NWS GFS MOS 2026-10-03T12Z, NWS National Blend of Models 2026-10-03T12Z | NWS GFS MOS 2026-10-03T18Z, NWS National Blend of Models 2026-10-03T18Z |
| PBE | 21% | 34% |
| Market at capture | 4% | 5% |
Evidence & method
What this story is based on. Every value above was read from these immutable records.
- Model
- pbe-weather-maxtemp@1.1.0 · RESEARCH
- Snapshot
- 323b9c0a-3737-4c36-8c8e-3aae46a7d126
- Compared with
- ab33501f-d2e6-476d-96e9-663fc8e6a80d
- Captured
- Oct 3 23:00Z
- Data cutoff
- Oct 3 23:00Z
- Market observation
- 5% · captured with the snapshot
- Source families
- NOAA/NWS via Iowa Environmental Mesonet archive · NOAA Regional Climate Centers ACIS · NOAA/NWS api.weather.gov
- Resolves on
- The Weather Company (weather.com/kalshi) — The Weather Company daily maximum temperature for CLIMDW (weather.com/kalshi)
- Independent check
- NWS Daily Climate Report CLIMDW (WFO LOT); NOAA RCC-ACIS USW00014819
- Measurement
- Maximum temperature for the climate day 2026-10-04, 00:00-24:00 local standard time (UTC-6)
- Rounding
- Whole degrees Fahrenheit as reported; preliminary values may differ by rounding/conversion
- Exceptions
- Preliminary data may be revised; the exchange may hold expiration until a non-erroneous revision, else last fair price
- Pre-window only; no current-conditions input
- Guidance can run cold/hot in unusual regimes (see LA diagnostic, 2026-10-04)
Weather · daily high — inputs: National Blend of Models day max (GFS MOS fallback) + station empirical guidance-error tables. This model on the research board →
Market prices are a benchmark only and never enter a PropBetEdge model. Research-stage probabilities; not advice.