Alright, Chicago, another Saturday is upon us, and if you thought about lacing up, you mostly picked a decent day to sweat, provided you know where to dodge the crowds and the stank.
- Your lungs are mostly in the clear with low AQI, but don't forget that moderate pollen count can still kick your allergies into high gear.
- Expect detours and crowds on major routes due to multiple races today, including a massive 10K, and ongoing trail construction.
- If you're near the South Side, be warned: the Thornton Reservoir is still holding onto some truly offensive odors from the recent deluges.
Look, the skies are overcast and the temp is a comfortable 19 degrees Celsius (that's 66 for you Fahrenheit holdouts), which is pretty prime running weather. Your AQI is sitting pretty at 34, so you can breathe easy on that front. But before you head out, remember it’s not all sunshine and PRs.
First, let's talk about the big one: today, July 11th, is race day for at least two major events. The BTN Big 10k, with over 10,000 participants, is hitting the streets of Chicago, and the smaller Mujeres on the Run is also happening. This means the usual suspects, like parts of the Lakefront Trail and various downtown streets, are going to be a mess. If you weren't registered, trying to weave through that human traffic is just asking for a collision or, worse, a pace-killing slow-down. Seriously, go another day or stick to quieter neighborhood streets.
Major races like the BTN Big 10k are happening today, July 11th, likely causing significant crowding and closures on the Lakefront Trail and city streets. Plan your route accordingly or prepare for unexpected detours.
And if you thought you could just escape to the tranquility of the Forest Preserves, think again. Construction is still ongoing on parts of the Des Plaines River Trail System, with closures from Ditka to Herrick Avenue and detours near Fullerton Avenue due to water main projects. Same goes for the Poplar Creek Trail System, which has a segment south of the Barrington Road and Golf Road intersection closed for another few weeks. That lovely run you had planned? Probably rerouted.
Then there’s the distinct "aroma" emanating from the Thornton Reservoir. After the excessive rains over the 4th of July weekend, that thing is still 85% full and has been described by locals as "horrific" and "putrid." The Metropolitan Water Reclamation District is trying to fix it with some odor mitigation systems, but that's a 2026 completion date for the projects, so don't expect any miracles today. If your route takes you anywhere near there, pack a nose plug or just avoid it entirely.
Avoid areas near the Thornton Reservoir on the South Side if you value your sense of smell. Reports indicate a "horrific" odor from near-capacity water levels.
On the bright side, wildfire smoke isn't an issue today, and we're not dealing with extreme heat. Just those good ol' Chicago construction delays, event congestion, and... well, that smell.
Pollen Breakdown
| Pollen Type | Level |
|---|---|
| Tree | Moderate |
| Grass | Moderate |
| Ragweed | Low |
With moderate tree and grass pollen, remember to take your allergy meds before you head out, especially if you're prone to sniffles and sneezes on your runs.
So, go ahead and get out there, but be smart about it. Check those routes, respect the road closures, and maybe carry a small bottle of Vicks VapoRub if you're venturing south. You've been warned.
Data grounded with National Weather Service Chicago/Romeoville IL, WTTW News, and Find A Race from July 10-11, 2026.