The Spread Maps Request an invite

Which weather model is most accurate in Chicago?

Forecast Highs Lows Rain Model accuracy

Chicago, Illinois · daily high temperature in °C · trailing 30 days, through Fri Oct 16

Every day, The Spread archives what each major weather model predicted for Chicago at 1-, 3-, and 7-day leads, then scores those forecasts against the MDW observations once the day has happened. This page covers the trailing 30 days (2026-09-17 to 2026-10-16), for daily high temperature.

One day out, too close to call; at three days, too close to call; at seven days, ECMWF AIFS (AI) (2.38°C).

The largest standing bias belongs to ECMWF AIFS (AI), which has run cool by about 1.11°C at 1-day lead over this window.

Chicago's full forecast, every model day by day, with the record on this page beside it. Request an invite; it's free during the beta.

The scoreboard

Typical miss (MAE) in °C with the bias in parentheses. Bias is the mean signed error of the predicted daily high — positive means the model ran warm. A model's high is the warmest of its hourly values and the station's is the warmest it got at any moment, so a model's high reads a little cool, and its low a little warm, even on a day it gets every hour right. ECMWF IFS gives a value only every 3 hours (every 6 past day 6), and ECMWF AIFS (AI) and NOAA AIGFS (AI) only every 6, with the hours between filled in, so their highs read cooler still and their lows warmer. In the forecasts scored here GFS also steps to every 3 hours from day 5, ICON and GEM from day 4, and UKMO from day 3, every 6 by day 6. Days = scored days behind the 1-day number.

Model 1-day 3-day 7-day Days
DWD ICON 1.0° (-0.3°) 1.6° (-0.6°) — 29
NOAA GFS 1.1° (+0.0°) 1.7° (+0.3°) 3.7° (+0.1°) 29
GEM (Canada) 1.1° (+0.6°) 2.0° (-0.5°) 2.8° (-1.2°) 29
NOAA AIGFS (AI) 1.3° (-1.1°) 1.6° (-0.3°) 3.6° (-0.4°) 29
ECMWF AIFS (AI) 1.4° (-1.1°) 1.6° (-1.0°) 2.4° (-1.5°) 29
UKMO (UK) 1.8° (-1.0°) 2.0° (-0.5°) — 29
ECMWF IFS 1.8° (-1.0°) 2.1° (-0.9°) 3.2° (-1.3°) 29

Method, honestly

The Spread's Chicago point is the Midway station (MDW), 15 km from downtown, used for both forecasts and verifications. Each forecast is the last one The Spread archived on the day it was made, the forecast the model was showing at the time, not a reconstruction. A day the station did not report is left out. Truth is the thermometer at Midway (MDW) — the station's own daily highs, a thermometer rather than a grid, and no correction applies: the thermometer is the truth outright. Rankings cover the models themselves; consensus products such as the NBM, itself a blend of models, are not scored here. A rolling 30-day window means these numbers move — that is the point.

Receipts — was the forecast right?

One page per settled date: what every model said as the day approached, what happened, and who was closest.

  • Fri Oct 16 14 days out the models said 8–16; it hit 14. AIGFS led (off 0.1°C); ECMWF ran 5°C warm.
  • Thu Oct 15 14 days out the models said 16–25; it hit 19. ICON led (off 0.1°C); GFS ran 2°C cool.
  • Wed Oct 14 14 days out the models said 10–26; it hit 19. AIFS led (off 0.1°C); GEM ran 2°C warm.
  • Tue Oct 13 14 days out the models said 15–19; it hit 26. ECMWF led (off 0.1°C); GEM ran 4°C warm.
  • Mon Oct 12 14 days out the models said 15–25; it hit 31. ICON led (off 0.3°C); ECMWF ran 4°C cool.
  • Sun Oct 11 14 days out the models said 12–18; it hit 26. GEM led (off 0.4°C); AIFS ran 3°C cool.
  • Sat Oct 10 14 days out the models said 14–25; it hit 27. ICON led (off 0.3°C); ECMWF ran 3°C cool.
  • Fri Oct 9 14 days out the models said 18–22; it hit 23. ICON led (off 0.2°C); UKMO ran 4°C cool.
  • Thu Oct 8 14 days out the models said 12–22; it hit 23. GEM led (off 0.2°C); ECMWF ran 3°C cool.
  • Wed Oct 7 14 days out the models said 17–22; it hit 26. AIGFS led (off 0.3°C); AIFS ran 3°C cool.
  • Tue Oct 6 13 days out the models said 18–21; it hit 23. GFS led (off 0.9°C); ECMWF ran 2°C cool.
  • Mon Oct 5 14 days out the models said 13–23; it hit 20. ICON led (off 0.3°C); ECMWF ran 2°C cool.
  • Sun Oct 4 14 days out the models said 16–23; it hit 23. GEM led (off 0.1°C); UKMO ran 3°C cool.
  • Sat Oct 3 14 days out the models said 16–21; it hit 21. GEM led (off 0.2°C); ECMWF ran 2°C cool.
  • Fri Oct 2 14 days out the models said 23–26; it hit 18. AIFS led (off 0.2°C); UKMO ran 2°C cool.
  • Thu Oct 1 14 days out the models said 18–27; it hit 22. ECMWF led (off 0.1°C); GFS ran 2°C cool.
  • Wed Sep 30 14 days out the models said 19–27; it hit 21. UKMO led (off 0.4°C); ICON ran 3°C cool.
  • Tue Sep 29 14 days out the models said 19–26; it hit 27. GEM led (off 0.2°C); AIFS ran 3°C cool.
  • Mon Sep 28 14 days out the models said 19–27; it hit 23. ICON led (off 0.4°C); UKMO ran 2°C cool.
  • Sun Sep 27 13 days out the models said 19–26; it hit 22. GFS led (off 0.1°C); UKMO ran 2°C cool.
  • Sat Sep 26 14 days out the models said 19–28; it hit 20. AIFS led (off 0.2°C); GFS ran 3°C warm.
  • Fri Sep 25 14 days out the models said 17–29; it hit 18. ECMWF led (off 0.2°C); GEM ran 2°C warm.
  • Thu Sep 24 14 days out the models said 16–29; it hit 21. GEM led (off 0.1°C); GFS ran 1°C warm.
  • Wed Sep 23 14 days out the models said 17–29; it hit 18. AIGFS led (off 0.0°C); GEM ran 2°C warm.
  • Tue Sep 22 14 days out the models said 20–23; it hit 18. GFS led (off 0.8°C); AIFS ran 2°C cool.
  • Mon Sep 21 14 days out the models said 20–28; it hit 18. ECMWF led (off 0.1°C); AIGFS ran 2°C cool.
  • Sun Sep 20 14 days out the models said 14–22; it hit 21. ECMWF led (off 0.0°C); UKMO ran 1°C warm.
  • Sat Sep 19 14 days out the models said 16–26; it hit 22. AIFS led (off 0.1°C); ICON ran 4°C warm.
  • Fri Sep 18 14 days out the models said 20–24; it hit 22. ICON led (off 0.1°C); GEM ran 2°C warm.
  • Thu Sep 17 14 days out the models said 19–23; it hit 28. GFS led (off 0.4°C); UKMO ran 6°C cool.
  • Wed Sep 16 14 days out the models said 20–29; it hit 24. ECMWF led (off 0.9°C); GFS ran 2°C cool.
  • Tue Sep 15 14 days out the models said 24–31; it hit 29. ECMWF led (off 0.8°C); AIFS ran 3°C cool.
  • Mon Sep 14 14 days out the models said 22–34; it hit 22. ICON led (off 0.1°C); GFS ran 3°C warm.
  • Sun Sep 13 14 days out the models said 25–33; it hit 24. AIGFS led (off 0.1°C); GEM ran 2°C warm.
  • Sat Sep 12 14 days out the models said 22–29; it hit 31. GFS led (off 0.6°C); AIFS ran 3°C cool.
  • Fri Sep 11 14 days out the models said 24–29; it hit 27. ICON led (off 0.2°C); AIFS ran 2°C cool.
  • Thu Sep 10 14 days out the models said 25–36; it hit 24. ECMWF led (off 0.1°C); GFS ran 3°C warm.
  • Wed Sep 9 14 days out the models said 20–29; it hit 27. UKMO led (off 0.4°C); AIGFS ran 2°C cool.
  • Tue Sep 8 14 days out the models said 24–30; it hit 31. GFS led (off 0.3°C); AIFS ran 4°C cool.
  • Mon Sep 7 14 days out the models said 27–31; it hit 27. UKMO led (off 0.4°C); ECMWF ran 2°C cool.
  • Sun Sep 6 14 days out the models said 24–28; it hit 26. GFS led (off 0.6°C); ECMWF ran 2°C cool.
  • Sat Sep 5 14 days out the models said 22–27; it hit 28. ICON led (off 0.3°C); ECMWF ran 2°C cool.
  • Fri Sep 4 14 days out the models said 21–24; it hit 34. GEM led (off 0.2°C); AIFS ran 3°C cool.
  • Thu Sep 3 14 days out the models said 25–35; it hit 33. ICON led (off 0.6°C); GEM ran 4°C warm.
  • Wed Sep 2 13 days out the models said 23–31; it hit 36. GFS led (off 0.1°C); AIFS ran 3°C cool.
  • Tue Sep 1 12 days out the models said 22–30; it hit 34. ICON led (off 0.1°C); AIFS ran 3°C cool.
  • Mon Aug 31 11 days out the models said 22–31; it hit 33. GEM led (off 0.1°C); AIFS ran 2°C cool.
  • Sun Aug 30 10 days out the models said 19–31; it hit 27. AIFS led (off 0.1°C); UKMO ran 4°C warm.
  • Sat Aug 29 9 days out the models said 21–28; it hit 28. ICON led (off 0.1°C); AIFS ran 2°C cool.
  • Fri Aug 28 8 days out the models said 20–27; it hit 29. GFS led (off 0.2°C); AIFS ran 2°C cool.
  • Thu Aug 27 7 days out the models said 22–30; it hit 27. ECMWF led (off 0.0°C); GFS ran 2°C warm.
  • Wed Aug 26 6 days out the models said 27–30; it hit 29. UKMO led (off 0.1°C); ECMWF ran 2°C cool.
  • Tue Aug 25 5 days out the models said 25–30; it hit 27. GFS led (off 0.0°C); AIFS ran 2°C cool.
  • Mon Aug 24 4 days out the models said 23–28; it hit 26. UKMO led (off 0.4°C); GEM ran 3°C warm.
  • Tue Aug 18 14 days out the models said 24–26; it hit 28. ICON led (off 0.4°C); AIFS ran 3°C cool.
  • Mon Aug 17 14 days out the models said 23–31; it hit 26. GEM led (off 0.1°C); GFS ran 2°C cool.
  • Sun Aug 16 14 days out the models said 22–28; it hit 31. GEM led (off 0.4°C); AIFS ran 3°C cool.
  • Sat Aug 15 14 days out the models said 25–28; it hit 29. UKMO led (off 0.2°C); AIGFS ran 5°C cool.
  • Fri Aug 14 14 days out the models said 19–28; it hit 25. ECMWF led (off 0.2°C); UKMO ran 2°C warm.
  • Thu Aug 13 14 days out the models said 22–28; it hit 26. UKMO led (off 0.3°C); AIFS ran 3°C cool.
  • Wed Aug 12 14 days out the models said 22–27; it hit 28. ICON led (off 0.1°C); GFS ran 4°C cool.
  • Tue Aug 11 14 days out the models said 22–36; it hit 26. ECMWF led (off 0.1°C); AIFS ran 2°C cool.
  • Mon Aug 10 14 days out the models said 25–30; it hit 29. AIGFS led (off 1.1°C); AIFS ran 3°C cool.
  • Sun Aug 9 14 days out the models said 26–34; it hit 26. ICON led (off 1.1°C); GEM ran 7°C warm.
  • Sat Aug 8 13 days out the models said 28–35; it hit 27. AIGFS led (off 0.3°C); UKMO ran 2°C warm.
  • Fri Aug 7 12 days out the models said 25–35; it hit 28. AIGFS led (off 0.0°C); GEM ran 3°C warm.
  • Thu Aug 6 11 days out the models said 23–35; it hit 26. AIFS led (off 0.6°C); GEM ran 2°C cool.
  • Wed Aug 5 10 days out the models said 28–33; it hit 29. UKMO led (off 0.1°C); AIFS ran 5°C cool.
  • Tue Aug 4 9 days out the models said 28–32; it hit 29. ECMWF led (off 0.2°C); GEM ran 3°C warm.
  • Mon Aug 3 8 days out the models said 27–33; it hit 26. GEM led (off 0.6°C); GFS ran 3°C cool.
  • Sun Aug 2 7 days out the models said 23–32; it hit 22. GFS led (off 0.0°C); GEM ran 3°C warm.
  • Sat Aug 1 6 days out the models said 23–31; it hit 22. ECMWF led (off 0.1°C); AIGFS ran 2°C cool.
  • Fri Jul 31 5 days out the models said 24–31; it hit 27. GFS led (off 0.3°C); UKMO ran 2°C warm.
  • Thu Jul 30 4 days out the models said 27–31; it hit 29. AIFS led (off 0.8°C); GFS ran 4°C cool.

Other cities

Atlanta, Georgia Berlin, State of Berlin Boston, Massachusetts Buffalo, New York Charlotte, North Carolina Dallas, Texas Denver, Colorado Detroit, Michigan Houston, Texas London, England Los Angeles, California Miami, Florida Milan, Lombardy Minneapolis, Minnesota New Orleans, Louisiana New York, New York Oklahoma City, Oklahoma Orlando, Florida Paris, Île-de-France Region Philadelphia, Pennsylvania Phoenix, Arizona Salt Lake City, Utah San Antonio, Texas San Diego, California San Francisco, California Seattle, Washington St. Louis, Missouri Tampa, Florida Washington, District of Columbia

The Spread — the forecast spread — is in closed beta. These verification pages are public while the rest is gated.