Bank of America Chicago Marathon weather.
Typically 15°C on race morning; rain in 3 of the last 10 years. Race morning (07:00 to 11:00 local time) in Chicago on race day in each of the last 10 years; the 2027 race is on 10 Oct 2027.
- Typical
- 15°C (59°F)
- race-morning average
- Coolest
- 4°C (39°F)
- lowest reading, 07:00–11:00
- Warmest
- 23°C (73°F)
- highest reading, 07:00–11:00
- Wet years
- 3 of 10
- rain, drizzle or worse
- Humidity
- 81%
- typical
- Wind
- 15 km/h
- typical, at 10 m
Race morning, 07:00–11:00
Year by year
| Race day | Average | Low–high | Humidity | Wind | Rain | Conditions |
|---|---|---|---|---|---|---|
| 11 Oct 2026 | 16°C (61°F) | 14°C (56°F)–18°C (65°F) | 85% | 5 km/h | 0.0 mm | Clear |
| 12 Oct 2025 | 12°C (54°F) | 11°C (51°F)–15°C (58°F) | 80% | 7 km/h | 0.0 mm | Clear |
| 13 Oct 2024 | 15°C (59°F) | 15°C (58°F)–15°C (60°F) | 87% | 14 km/h | 0.2 mm | Light drizzle |
| 8 Oct 2023 | 9°C (49°F) | 8°C (46°F)–11°C (51°F) | 69% | 16 km/h | 0.0 mm | Overcast |
| 9 Oct 2022 | 10°C (51°F) | 7°C (45°F)–15°C (58°F) | 55% | 20 km/h | 0.0 mm | Clear |
| 10 Oct 2021 | 22°C (71°F) | 21°C (69°F)–23°C (73°F) | 80% | 27 km/h | 0.0 mm | Overcast |
| 11 Oct 2020 | 16°C (60°F) | 15°C (58°F)–16°C (62°F) | 88% | 14 km/h | 0.6 mm | Light drizzle |
| 13 Oct 2019 | 6°C (43°F) | 4°C (39°F)–9°C (48°F) | 69% | 23 km/h | 0.0 mm | Mainly clear |
| 7 Oct 2018 | 15°C (59°F) | 15°C (58°F)–16°C (61°F) | 89% | 18 km/h | 5.0 mm | Light rain |
| 8 Oct 2017 | 16°C (62°F) | 13°C (56°F)–20°C (68°F) | 81% | 11 km/h | 0.0 mm | Clear |
Each row is the race's date that year where we know it, else the same weekday nearest its usual date. Temperatures and humidity are averaged over 07:00 to 11:00 local time, rain is the total over those hours, and conditions are the commonest over the morning. The marathon starts at 07:30.
Kit and pacing
What it means
Mild: start a touch conservatively
Around 15°C feels fine at the start but warms up by the second half. Drink from the early stations rather than waiting until you're thirsty, and wear the lightest kit you have.
Have a warm-day plan
In the warmest of these years it reached 23°C by late morning. Decide in advance how much you'd slow down if the forecast is warm, rather than on the course.
Be ready for rain
It rained on 3 of the last 10 race mornings. A bin bag or cheap poncho keeps you dry in the start pen; anti-chafe balm and socks that don't hold water help over the distance, and a cap keeps rain out of your eyes.
Humid mornings
Humidity is usually around 81%, so sweat evaporates slowly and it feels warmer than the thermometer says. Pace on effort, not just the watch.
Expect wind
Wind was 15 km/h on a typical morning here. Run in a group on exposed stretches, and aim for even effort rather than even splits: time lost into a headwind isn't all won back with it behind you.
The weather varies a lot
Race mornings here have ranged by 15°C from year to year. Pack for both, and settle your kit and pacing from the forecast in the last few days.
General guidance from past years' numbers. Check the forecast in race week.
Weather data by Open-Meteo.com, from its historical weather archive (CC BY 4.0).