Race-day weather · Wyndo for runners
Chicago Marathon weather
October 11, 2026 · Chicago, IL · scheduled start 7:30 AM (America/Chicago). What the start usually feels like, year by year — and a live start-time read once the race is inside the 7-day forecast window.
This edition has run
The 2026 Chicago Marathon is behind us
The next edition typically follows the race's pattern — 2nd Sunday of October (official policy, published through 2036). We'll flip this page to the new date (and the live start-time read for race week) when the race confirms its schedule. The history below keeps the long view.
Race-morning weather history
2007 race hit ~88F heat and was halted mid-race with hundreds treated; 2010 also ran hot. Wyndo tracks what this calendar slot has actually served up at the start hour — temperature, dew point, wind, and rain — including the years when weather canceled or disrupted the race, and reads the live forecast for the start once race week arrives.
Median start temp
53°F
p75 (a warm year): 57°F
Median dew point
46°F
at the start hour
Rain at the start
5%
1 of 20 measured years
Warmest start
70°F
in 2021
Scroll sideways to see all columns.
| Year | Start temp | Dew point | Wind | Precip (start hr) | Day's high |
|---|---|---|---|---|---|
| 2025 | 52°F | 48°F | 6 mph | dry | 65°F |
| 2024 | 57°F | 53°F | 5 mph | dry | 64°F |
| 2023 | 46°F | 38°F | 10 mph | dry | 54°F |
| 2022 | 44°F | 32°F | 11 mph | dry | 67°F |
| 2021 | 70°F | 65°F | 16 mph | dry | 76°F |
| 2020 | 57°F | 53°F | 8 mph | dry | 66°F |
| 2019 | 42°F | 33°F | 10 mph | dry | 52°F |
| 2018 | 42°F | 38°F | 3 mph | dry | 56°F |
| 2017 | 55°F | 51°F | 7 mph | dry | 75°F |
| 2016 | 52°F | 48°F | 6 mph | dry | 61°F |
| 2015 | 53°F | 45°F | 13 mph | dry | 75°F |
| 2014 | 42°F | 37°F | 10 mph | dry | 60°F |
| 2013 | 48°F | 41°F | 8 mph | dry | 63°F |
| 2012 | 64°F | 61°F | 16 mph | 4.2 mm | 66°F |
| 2011 | 55°F | 51°F | 4 mph | dry | 76°F |
| 2010 | 60°F | 52°F | 6 mph | dry | 81°F |
| 2009 | 33°F | 22°F | 8 mph | dry | 44°F |
| 2008 | 60°F | 55°F | 6 mph | dry | 79°F |
| 2007 | 56°F | 45°F | 7 mph | dry | 61°F |
| 2006 | 48°F | 42°F | 9 mph | dry | 71°F |
Slot climatology: each row is the weather at this race's usual calendar slot and start hour (ERA5 reanalysis at the start line) — including years when the edition was canceled or moved. A computed slot date is not a claim the race ran that day.
Your heat-adjusted goal for the marathon
The same cited model as the full calculator, pointed at this race: the median start-hour conditions this calendar slot has served up — climatology, not a forecast.
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Race facts
- Start line
- Grant Park, Columbus Drive at Monroe Street
- Scheduled start
- 7:30 AM (America/Chicago) — Official 2026 race-day timeline: wheelchair 07:20/07:21, handcycle 07:23, professional field and Wave 1 07:30, Wave 2 08:00, Wave 3 08:35.
- Field size
- 2025 finishers ~54,350 (event record); 2024 ~52,150
- Registration
- lottery + time qualifier + legacy + charity
Wyndo is not affiliated with or endorsed by the Chicago Marathon (officially the "Bank of America Chicago Marathon") or its organizers. Race names are used descriptively to identify the event; schedules and start times belong to the race — always confirm details on the official site. Weather guidance here is informational, never medical advice, and event alert flags on race day belong to the race's own medical team.