Chicago Half Marathon weather
What will race morning in Chicago cost you?
Chicago Half Marathon mornings around race day since 2021, by weather-model estimate: about 60°F (15°C) at 07:00 near Chicago. Most were 52 to 66°F.
- Date
- Sun, 27 Sept 2026
- First start
- 07:15 local
- Distance
- 13.1 mi
| Year | Air | Dew pt | Wind | Rain hrs |
|---|---|---|---|---|
| 2025 | 62°F | 58°F | 6 mph | 0% |
| 2024 | 62°F | 57°F | 8 mph | 27% |
| 2023 | 63°F | 59°F | 6 mph | 27% |
| 2022 | 53°F | 46°F | 9 mph | 18% |
| 2021 | 59°F | 51°F | 10 mph | 0% |
By weather-model estimate near the race, mornings around race day. Not station readings.
The Life Time Chicago Half Marathon uses a flat route with a traffic-restricted stretch of Lake Shore Drive. Confirm the current course map and start instructions with the organiser. Organiser route
Past starts: 60°F typical, 52 to 66°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
2:00:00 goal. On a typical race morning here, expect about 2:01 to 2:05. Main factor: heat.
- Heat and sun+2%
- Wind and comfort+1%
- Weather total+3%
RunWeather’s pace model at your goal effort, over every hour you are on course (07:15 to 09:15 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 |
| 13.1 mi · Finish | 2:00:00 |
In the app
Your race plan, on race morning
Add the Chicago Half 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 day recap27 September 2026
Chicago Half Marathon ran on 27 September 2026. The weather recap for this edition is not published yet.
The course13.1 mi
The Life Time Chicago Half Marathon uses a flat route with a traffic-restricted stretch of Lake Shore Drive. Confirm the current course map and start instructions with the organiser.
RACE MORNING AT 07:152021–202552–66°FWhere most starts fell, in the weather near Chicago around race day. Not a forecast.
- AVERAGE
- 60°F
- HUMIDITY
- 84%
- WIND
- 8 mph
Official race site ↗01Check the wind forecast for the exposed Lake Shore Drive section before locking in an opening effort.
02Compare the conditions at your start and expected finish before settling on kit and effort.
03Confirm late changes to the route, start wave and logistics with the organiser.
Race-window historyLast 5 years, race date ±5 days
A range for planning Chicago Half Marathon: weather near Chicago on race morning, the last 5 years (2021 to 2025, race date ±5 days). Not a forecast.
Typical start-hour air60°F10th–90th percentile 52°F–66°FDew point / humidity55°F84% relative humidityStart-hour wind8 mphDirection varies by dayHours with rain15%Historical frequency at this hourAIR THROUGH THE RUN60°F → 68°F by +4hThe five-year picture
07:00- Air temperature
- 60°F
- Humidity
- 84%
- Wind
- 8 mph
- Hours with rain
- 15%
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 8°F across four hours. Check your expected finish-hour forecast, not just the start.
WIND CONTEXTWhere the breeze came from
WIND FROMNE10 of 55 samples · 18%
Mean 8 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 07:00 local time, across 11 calendar days per year in 2021–2025. The sample uses the hour containing the advertised first start; waves may start later. Grid weather is modelled reanalysis, not an on-course station reading. Open-Meteo Historical Weather API . Data generated 2026-10-12.
September climateAll-hours monthly averages
September averages in Chicago, from 2022 to 2024. These are monthly conditions, not a race-day forecast.
- mean temperature
- 67°F
- mean humidity
- 73%
- mean wind
- 9 mph
- hours with rain
- 12%
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 Half Marathon FAQs7 questions
When is the 2026 Chicago Half Marathon?
Chicago Half Marathon is listed for 27 September 2026. Confirm the latest details on the official event website before travelling.
Is the weather shown a forecast for the Chicago Half 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 Half Marathon?
Around the 07:15 start, mornings around race day near Chicago in the last 5 years averaged 60°F (15°C), 84% humidity and 13 km/h wind. Most started between 52°F and 66°F. This is weather near the city, not a reading from the race itself or a forecast.
Which recent year had the warmest race morning at the Chicago Half Marathon?
2023. Around race day that year it was about 63°F (17°C) around the 07:15 start, against 60°F (15°C) on an average year.
Which recent year had the windiest race morning at the Chicago Half Marathon?
2021, with about 16 km/h of wind around the 07:15 start. Over the last 5 years the wind here came mostly from the north-east.
How should I pace the Chicago Half Marathon on a warm day?
2:00:00 goal. On a typical race morning here, expect about 2:01 to 2:05. 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 Half 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 2026-10-12
Past race-morning weather: Open-Meteo Historical Weather API, weather near the city from 2021 to 2025, updated 2026-10-12. 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.
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