Chicago Marathon weather
What will race morning in Chicago cost you?
Chicago Marathon race mornings since 2021 at Chicago Midway airport: typically 60°F (16°C) at 07:35. Race days ran 47 to 72°F.
- Date
- Sun, 11 Oct 2026
- First start
- 07:35 local
- Distance
- 26.2 mi
| Year | Air | Dew pt | High by 11:35 | Rain |
|---|---|---|---|---|
| 2026 11 Oct | 60°F | 53°F | 67°F | None |
| 2025 12 Oct | 52°F | 47°F | 62°F | None |
| 2024 13 Oct | 60°F | 53°F | 61°F | None |
| 2023 8 Oct | 47°F | 37°F | 53°F | None |
| 2022 9 Oct | 47°F | 32°F | 60°F | None |
| 2021 10 Oct | 72°F | 61°F | 75°F | None |
Chicago Midway airport station on each race date.
Chicago follows a flat loop through 29 neighbourhoods, starting and finishing in Grant Park. The map is a past course. Check the organiser's map for this year. Organiser route
Past starts: 60°F typical, 47 to 72°F since 2021.
01 · The conditions
Race-day weather
The past weather below is context for the next edition. We do not substitute today’s weather for a past race.
Explore historical weather- ★★★★★5.080+ ratings
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Example race: a hot half marathon in Florida
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Works with Apple HealthGet Chicago race-morning weather on your phone.
The app turns race-morning weather into your race plan: your goal pace, your race-day pace, and how to spend it from the start to the finish.
On a computer? Scan with your phone camera to get the app.
Example race: a hot half marathon in Florida
02 · Same effort, different day
What the weather may cost your goal
4:00:00 goal. On a typical race morning here, expect about 4:02 to 4:10. Main factor: heat.
- Heat and sun+2%
- Wind and comfort0%
- Weather total+2%
RunWeather’s pace model at your goal effort, over every hour you are on course (09:00 to 13:00 local), weighted by the time you spend in each, using the five-year race-morning average. A planning preview, not a predicted finish. Hills, turns, shelter, fuelling and heat adaptation are not modelled here; rain is left out because a probability is not a measured rain rate. Explore the heat pace calculator.
View even-pace checkpoints
| Distance | Elapsed time |
|---|---|
| 3.1 mi | 0:28:26 |
| 6.2 mi | 0:56:53 |
| 9.3 mi | 1:25:19 |
| 12.4 mi | 1:53:45 |
| 15.5 mi | 2:22:12 |
| 18.6 mi | 2:50:38 |
| 21.7 mi | 3:19:05 |
| 24.9 mi | 3:47:31 |
| 26.2 mi · Finish | 4:00:00 |
In the app
Your race plan, on race morning
Add the Chicago Marathon and the app keeps your plan current until the gun.
Goal pace against race-day pace
What your goal is worth on this morning’s weather, per mi and at the finish.
How to spend it
Start, middle and finish, against your average.
What slows you
Heat, wind and hills, each in minutes.
Goal vs race day
What slows you
Example race: a hot half marathon in Florida
Reference
Everything else about race morning
Open any row for the full detail.
Race morning ran warmer than forecast11 October 2026
Observed, Chicago Midway airportForecast the day beforeFinishers in 3h30 to 5h00It ran up to 3°F warmer than the forecast the day before. The day warmed 14°F between the first start and the late finishes, so the second half was the warm half. Holding effort steady and letting pace drift late suited the day better than even pace from the gun.
Observed: hourly reports from the Chicago Midway airport (MDW) weather station, about 15 km from the start. Forecast: city forecast as issued the day before the race. W1 to W3 mark wave starts (07:35, 08:00, 08:35). Not official race measurements.
Chicago Marathon weather by yearSince 2015 · 41 to 72°F at the start
Weather on each race date at Chicago Midway airport, 07:35, this year's first-wave start. 11 races, 41°F to 72°F at the start.
Coolest start41°FTypical start54°FWarmest start72°FChicago Marathon race-morning weather by year at Chicago Midway airport Year Air 07:35 Dew pt High to 11:35 Rain 2026Oct 11 60°F 53°F 67°F None 2025Oct 12 52°F 47°F 62°F None 2024Oct 13 60°F 53°F 61°F None 2023Oct 8 47°F 37°F 53°F None 2022Oct 9 47°F 32°F 60°F None 2021Oct 10 72°F 61°F 75°F None 2020 Cancelled. No race was held. 2019Oct 13 41°F 32°F 48°F None 2018Oct 7 59°F 56°F 60°F 0.06 in 2017Oct 8 57°F 54°F 69°F None 2016Oct 9 51°F 45°F 58°F None 2015Oct 11 54°F 44°F 68°F None Hourly reports from the Chicago Midway airport weather station (MDW), about 15 km from the course point, via the Iowa Environmental Mesonet archive. 07:35 is this year's first-wave start; earlier start times are not all verified, so every year is read at the same clock. High and rain cover 07:35 to 11:35. Race dates: World Athletics, AIMS or the organiser. Not a forecast. Data generated 2026-10-20.
The course26.2 mi
Chicago follows a flat loop through 29 neighbourhoods, starting and finishing in Grant Park. The map is a past course. Check the organiser's map for this year.
THE COURSE26.2 mi1×Zoom to drag the route. Keyboard: + / −, arrows, Home to reset.
2025 course. Check the organiser’s map for this year.
Official race site ↗01Match the forecast to your assigned wave rather than the first start of the morning.
02Check wind as well as air temperature before setting your effort for the day.
03Use official course markers to assess pace when GPS readings drift around tall buildings.
Race-window historyLast 5 years, race date ±5 days
A range for planning Chicago Marathon: weather near Chicago on race morning, the last 5 years (2021 to 2025, race date ±5 days). Not a forecast.
Typical start-hour air56°F10th–90th percentile 46°F–65°FDew point / humidity47°F74% relative humidityStart-hour wind10 mphDirection varies by dayHours with rain18%Historical frequency at this hourAIR THROUGH THE RUN56°F → 62°F by +4hThe five-year picture
09:00- Air temperature
- 56°F
- Humidity
- 74%
- Wind
- 10 mph
- Hours with rain
- 18%
Hover or drag to explore. Use ← → when focused. Shading: middle 80% of sampled temperatures.
Five-year average Middle 80% of sampled hoursThe sampled air warms by about 6°F across four hours. Check your expected finish-hour forecast, not just the start.
WIND CONTEXTWhere the breeze came from
WIND FROMN9 of 55 samples · 16%
Mean 12 mphThe petals show how often the wind came from each direction at the sampled start hour. They do not predict the direction on race day.
A city-point wind rose cannot tell you which parts of the course will be sheltered or exposed. Use the live forecast and the organiser’s route map together.
Method: 55 ERA5 hourly samples at 09:00 local time, across 11 calendar days per year in 2021–2025. A 09:00 sample is used because the organiser has not confirmed a first start in this guide. Grid weather is modelled reanalysis, not an on-course station reading. Open-Meteo Historical Weather API . Data generated 2026-09-29.
October climateAll-hours monthly averages
October averages in Chicago, from 2022 to 2024. These are monthly conditions, not a race-day forecast.
- mean temperature
- 55°F
- mean humidity
- 68%
- mean wind
- 12 mph
- hours with rain
- 15%
Monthly, all-hours averages for Chicago, 2022–2024. Not past race-day measurements or a forecast. Rain is the share of historical hours with precipitation, not the chance of rain on race day. Source: Open-Meteo ERA5.
Explore running weather in ChicagoChicago Marathon FAQs7 questions
When is the 2026 Chicago Marathon?
Chicago Marathon is scheduled for 11 October 2026. Confirm the latest details on the official event website before travelling.
Is the weather shown a forecast for the Chicago Marathon?
Only from about 14 days before the race, when the page shows the live race-day forecast. Before that, you see the weather near the city on the mornings around race day in the last 5 years: what is typical, not what will happen. Monthly averages, when shown, cover every hour of the race month.
What is race morning usually like at the Chicago Marathon?
At 07:35, race mornings since 2021 at Chicago Midway airport were typically 60°F (16°C), from 47 to 72°F. Around race day the weather-model estimate near Chicago averaged 74% humidity and 16 km/h wind. These are past readings, not a forecast.
Which recent year had the warmest race morning at the Chicago Marathon?
2021. At 07:35 that race morning Chicago Midway airport read about 72°F (22°C), against 60°F (16°C) in a typical year.
Which recent year had the windiest race morning at the Chicago Marathon?
2023, with about 19 km/h of wind at 09:00 (the start time is not confirmed). Over the last 5 years the wind here came mostly from the north.
How should I pace the Chicago Marathon on a warm day?
4:00:00 goal. On a typical race morning here, expect about 4:02 to 4:10. Main factor: heat. On a warm day, start about 15 s/km easier than goal pace, run by feel to halfway and drink early. Plan my race gives your splits for the day.
Can past years predict the weather on race day at the Chicago Marathon?
No. They show what race morning is usually like, not what this year will bring. Check the live forecast in the last 14 days, look at the hours through your expected finish, and follow the organiser for start and course updates.
Sources and race informationOrganiser, weather data, guide reviewed 2026-09-22
Past race-morning weather: Open-Meteo Historical Weather API, weather near the city from 2021 to 2025, updated 2026-09-29. Not official race-day readings.
Guide reviewed . RunWeather is an independent guide, not the race organiser. Dates, waves and routes can change; the organiser’s latest instructions take priority. Course map: The 2025 course from RunWeather's race catalogue. The next edition may differ; elevation is approximate.
Chicago race morning, on your phone.
Free on iPhone and Android. Your race plan, updated with the forecast until the gun.
On a computer? Scan with your phone camera to get the app.
Example race: a hot half marathon in Florida